There is observational evidence that global sealevel is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sealevelrise is currently increasing and, if so, by how much. Here we provide new insights into sealevelaccelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sealevel records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sealevelacceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sealevel records. PMID:24728012

There is observational evidence that global sealevel is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sealevelrise is currently increasing and, if so, by how much. Here we provide new insights into sealevelaccelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sealevel records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sealevelacceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sealevel records.

Global mean sealevelrise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sealevelrise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade. PMID:27506974

Global mean sealevelrise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sealevelrise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade.

Measuring sealevel change and understanding its causes has considerably improved in the recent years, essentially because new in situ and remote sensing observations have become available. Here we report on most recent results on contemporary sealevelrise. We first present sealevel observations from tide gauges over the twentieth century and from satellite altimetry since the early 1990s. We next discuss the most recent progress made in quantifying the processes causing sealevel change on timescales ranging from years to decades, i.e., thermal expansion of the oceans, land ice mass loss, and land water-storage change. We show that for the 1993-2007 time span, the sum of climate-related contributions (2.85 +/- 0.35 mm year(-1)) is only slightly less than altimetry-based sealevelrise (3.3 +/- 0.4 mm year(-1)): approximately 30% of the observed rate of rise is due to ocean thermal expansion and approximately 55% results from land ice melt. Recent acceleration in glacier melting and ice mass loss from the ice sheets increases the latter contribution up to 80% for the past five years. We also review the main causes of regional variability in sealevel trends: The dominant contribution results from nonuniform changes in ocean thermal expansion.

Sealevelrise becomes our concern nowadays as a result of variously contribution of climate change that cause by the anthropogenic effects. Global sealevels have been rising through the past century and are projected to rise at an accelerated rate throughout the 21st century. Due to this change, sealevel is now constantly rising and eventually will threaten many low-lying and unprotected coastal areas in many ways. This paper is proposing a significant effort to quantify the sealevel trend over Malaysian seas based on the combination of multi-mission satellite altimeters over a period of 23 years. Eight altimeter missions are used to derive the absolute sealevel from Radar Altimeter Database System (RADS). Data verification is then carried out to verify the satellite derived sealevelrise data with tidal data. Eight selected tide gauge stations from Peninsular Malaysia, Sabah and Sarawak are chosen for this data verification. The pattern and correlation of both measurements of sealevel anomalies (SLA) are evaluated over the same period in each area in order to produce comparable results. Afterwards, the time series of the sealevel trend is quantified using robust fit regression analysis. The findings clearly show that the absolute sealevel trend is rising and varying over the Malaysian seas with the rate of sealevel varies and gradually increase from east to west of Malaysia. Highly confident and correlation level of the 23 years measurement data with an astonishing root mean square difference permits the absolute sealevel trend of the Malaysian seas has raised at the rate 3.14 ± 0.12 mm yr-1 to 4.81 ± 0.15 mm yr-1 for the chosen sub-areas, with an overall mean of 4.09 ± 0.12 mm yr-1. This study hopefully offers a beneficial sealevel information to be applied in a wide range of related environmental and climatology issue such as flood and global warming.

Published values for the long-term, global mean sealevelrise determined from tide gauge records exhibit considerable scatter, from about 1 mm to 3 mm/yr. This disparity is not attributable to instrument error; long-term trends computed at adjacent sites often agree to within a few tenths of a millimeter per year. Instead, the differing estimates of global sealevelrise appear to be in large part due to authors' using data from gauges located at convergent tectonic plate boundaries, where changes of land elevation give fictitious sealevel trends. In addition, virtually all gauges undergo subsidence or uplift due to postglacial rebound (PGR) from the last deglaciation at a rate comparable to or greater than the secular rise of sealevel. Modeling PGR by the ICE-3G model of Tushingham and Peltier (1991) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sealevel records. The value for mean sealevelrise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 is 1.8 mm/yr {plus minus} 0.1. This result provides confidence that carefully selected long tide gauge records measure the same underlying trend of sealevel and that many old tide gauge records are of very high quality.

The distribution of New England salt marsh communities is intrinsically linked to the magnitude, frequency, and duration of tidal inundation. Cordgrass (Spartina alterniflora) exclusively inhabits the frequently flooded lower elevations, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus gerardi) typically dominate higher elevations. Monitoring plant zonal boundaries in two New England salt marshes revealed that low-marsh cordgrass rapidly moved landward at the expense of higher-marsh species between 1995 and 1998. Plant macrofossils from sediment cores across modern plant community boundaries provided a 2,500-year record of marsh community composition and documented the migration of cordgrass into the high marsh. Isotopic dating revealed that the initiation of cordgrass migration occurred in the late 19th century and continued through the 20th century. The timing of the initiation of cordgrass migration is coincident with an acceleration in the rate of sea-levelrise recorded by the New York tide gauge. These results suggest that increased flooding associated with accelerating rates of sea-levelrise has stressed high-marsh communities and promoted landward migration of cordgrass. If current rates of sea-levelrise continue or increase slightly over the next century, New England salt marshes will be dominated by cordgrass. If climate warming causes sea-levelrise rates to increase significantly over the next century, these cordgrass-dominated marshes will likely drown, resulting in extensive losses of coastal wetlands.

Within intertidal communities, aerial exposure (emergence during the tidal cycle) generates strong vertical zonation patterns with distinct growth boundaries regulated by physiological and external stressors. Forecasted accelerations in sea-levelrise (SLR) will shift the position of these critical boundaries in ways we cannot yet fully predict, but landward migration will be impaired by coastal development, amplifying the importance of foundation species’ ability to maintain their position relative to risingsealevels via vertical growth. Here we show the effects of emergence on vertical oyster-reef growth by determining the conditions at which intertidal reefs thrive and the sharp boundaries where reefs fail, which shift with changes in sealevel. We found that oyster reef growth is unimodal relative to emergence, with greatest growth rates occurring between 20–40% exposure, and zero-growth boundaries at 10% and 55% exposures. Notably, along the lower growth boundary (10%), increased rates of SLR would outpace reef accretion, thereby reducing the depth range of substrate suitable for reef maintenance and formation, and exacerbating habitat loss along developed shorelines. Our results identify where, within intertidal areas, constructed or natural oyster reefs will persist and function best as green infrastructure to enhance coastal resiliency under conditions of accelerating SLR. PMID:26442712

Within intertidal communities, aerial exposure (emergence during the tidal cycle) generates strong vertical zonation patterns with distinct growth boundaries regulated by physiological and external stressors. Forecasted accelerations in sea-levelrise (SLR) will shift the position of these critical boundaries in ways we cannot yet fully predict, but landward migration will be impaired by coastal development, amplifying the importance of foundation species' ability to maintain their position relative to risingsealevels via vertical growth. Here we show the effects of emergence on vertical oyster-reef growth by determining the conditions at which intertidal reefs thrive and the sharp boundaries where reefs fail, which shift with changes in sealevel. We found that oyster reef growth is unimodal relative to emergence, with greatest growth rates occurring between 20-40% exposure, and zero-growth boundaries at 10% and 55% exposures. Notably, along the lower growth boundary (10%), increased rates of SLR would outpace reef accretion, thereby reducing the depth range of substrate suitable for reef maintenance and formation, and exacerbating habitat loss along developed shorelines. Our results identify where, within intertidal areas, constructed or natural oyster reefs will persist and function best as green infrastructure to enhance coastal resiliency under conditions of accelerating SLR.

The Army Corps of Engineers, Pacific Ocean Division, participated in the interagency case study of sealevelrise for Yap State in the Federated States of Micronesia. The study, on behalf of the National Oceanic and Atmospheric Administration, was in support of the Intergovernmental Panel on Climate Change. Engineering and environmental analyses indicate that resources within Yap State at risk from a 1.0 meter rise in sealevel by the year 2100 are substantial, including coral reefs, sea grass beds, wetlands, native mangrove forests, groundwater, archaeological and cultural resources, and shoreline infrastructure. Severe constraints associated with land ownership patterns have helped prevent the potential for greater impact. Yet these same constraints will likely hinder future decisions regarding retreat, accommodation, or protection strategies. As a result, there are special institutional and cultural challenges that face Yap in developing and implementing appropriate responses to acceleratedsealevelrise. These are made more difficult with the many uncertainties associated with current predictions regarding the greenhouse effect.

Climate warming does not force sea-levelrise (SLR) at the same rate everywhere. Rather, there are spatial variations of SLR superimposed on a global average rise. These variations are forced by dynamic processes, arising from circulation and variations in temperature and/or salinity, and by static equilibrium processes, arising from mass redistributions changing gravity and the Earth's rotation and shape. These sea-level variations form unique spatial patterns, yet there are very few observations verifying predicted patterns or fingerprints. Here, we present evidence of recently accelerated SLR in a unique 1,000-km-long hotspot on the highly populated North American Atlantic coast north of Cape Hatteras and show that it is consistent with a modelled fingerprint of dynamic SLR. Between 1950–1979 and 1980–2009, SLR rate increases in this northeast hotspot were ~ 3–4 times higher than the global average. Modelled dynamic plus steric SLR by 2100 at New York City ranges with Intergovernmental Panel on Climate Change scenario from 36 to 51 cm (ref. 3); lower emission scenarios project 24–36 cm (ref. 7). Extrapolations from data herein range from 20 to 29 cm. SLR superimposed on storm surge, wave run-up and set-up will increase the vulnerability of coastal cities to flooding, and beaches and wetlands to deterioration.

Tidal wetland ecosystems are dynamic coastal habitats that, in California, often occur at the complex nexus of aquatic environments, diked and leveed baylands, and modified upland habitat. Because of their prime location and rich peat soil, many wetlands have been reduced, degraded, and/or destroyed, and yet their important role in carbon sequestration, nutrient and sediment filtering, and as habitat requires us to further examine their sustainability in light of predicted climate change. Predictions of climate change effects for the San Francisco Bay Estuary present a future with reduced summer freshwater input and increased sealevels. We examined the applicability and accuracy of the Marsh Equilibrium Model (MEM), a zero-dimensional model that models organic and inorganic accretion rates under a given rate of sea-levelrise. MEM was calibrated using data collected from salt and brackish marshes in the San Francisco Bay Estuary to examine wetland resiliency under a range of sea-levelrise and suspended sediment concentration scenarios. At sea-levelrise rates 100 cm/century and lower, wetlands remained vegetated. Once sealevelsrise above 100 cm, marshes begin to lose ability to maintain elevation, and the presence of adjacent upland habitat becomes increasingly important for marsh migration. The negative effects of sea-levelrise on elevations were compounded as suspended sediment concentrations decreased. Results from this study emphasize that the wetland landscape in the bay is threatened with risingsealevels, and there are a limited number of wetlands that will be able to migrate to higher ground as sealevelsrise.

The US Atlantic coast is one of the most vulnerable areas to sealevelrise (SLR) due to its low elevation, large population concentrations, and economic importance. Further vulnerability arises from accelerating rates of SLR, which began in the early 2000's and caused a significant increase in flooding frequency in several coastal communities. Several studies have suggested that the accelerating SLR rates are due to the slowing down of the Atlantic Meridional Overturning Circulation, in particular, a weakening of the Gulf Stream (GS). However, there are no direct observations that link the GS conditions and high sealevels along the coast. In this study we use satellite altimetry, tide gauge, and Florida Current (FC) cable data to explore possible relations between the recent SLR rate increase along the Florida Atlantic coast and various dynamical processes in the GS/FC system. Preliminary calculations indicate a good agreement between coastal sealevel and nearshore altimetry series (R = 0.76-0.8) suggesting that SSH gradients from altimetry may be useful for assessing the dynamics associated with the coastal sealevel change. Here we focus on spatio-temporal SSH changes along the two satellite passes located closest to the Florida Atlantic coast. Our results indicate an intriguing transition in SSH behavior around 2004-5. Prior to 2004, anomalous low coastal SSH events (strong FC) occurred every 3-5 years in correlation with warm ENSO events. After 2004, the strong relationship between ENSO and the gradient across the FC vanishes, while the mean sealevel across the current increases. The observed SSH anomaly transition around 2004-5 correlates well with the initiation of accelerated rates of coastal SLR, suggesting that the decadal scale SLR acceleration has occurred during weak FC conditions. However, the forcing of this transition and the role of mean sealevel variability, which is of comparable magnitude to variability in the gradient, remain unexplained.

Expanding hypoxia is today a major threat for many coastal seas around the world and disentangling its drivers is a large challenge for interdisciplinary research. Using a coupled physical-biogeochemical model we estimate the impact of past and accelerated future global mean sealevelrise (GSLR) upon water exchange and oxygen conditions in a semi-enclosed, shallow sea. As a study site, the Baltic Sea was chosen that suffers today from eutrophication and from dead bottom zones due to (1) excessive nutrient loads from land, (2) limited water exchange with the world ocean and (3) perhaps other drivers like global warming. We show from model simulations for the period 1850-2008 that the impacts of past GSLR on the marine ecosystem were relatively small. If we assume for the end of the twenty-first century a GSLR of +0.5 m relative to today's mean sealevel, the impact on the marine ecosystem may still be small. Such a GSLR corresponds approximately to the projected ensemble-mean value reported by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. However, we conclude that GSLR should be considered in future high-end projections (>+1 m) for the Baltic Sea and other coastal seas with similar hydrographical conditions as in the Baltic because GSLR may lead to reinforced saltwater inflows causing higher salinity and increased vertical stratification compared to present-day conditions. Contrary to intuition, reinforced ventilation of the deep water does not lead to overall improved oxygen conditions but causes instead expanded dead bottom areas accompanied with increased internal phosphorus loads from the sediments and increased risk for cyanobacteria blooms.

A "hotspot" of acceleratedsealevelrise has recently been reported along the east coast of the United States, potentially linked with slowdown of the Atlantic Meridional Overturning Circulation in a warming climate. However, separating acceleration in the long-term trend from transient acceleration due to natural variability - particularly the approximately 60-year cycle associated with the Atlantic Multidecadal Oscillation - poses technical difficulties. The Empirical Mode Decomposition (EMD) and Ensemble EMD (EEMD) methods have been used to isolate the nonlinear trend from oscillations on various timescales, allowing robust acceleration estimates for the trend. Yet the accuracy of these methods in detecting acceleratedsealevelrise, particularly given the limited lengths of available tide gauge records, has not yet been fully justified. In this study, idealized sealevel time series are constructed based upon interannual, decadal, and multidecadal oscillations obtained from tide gauge observations and prescribed trends with known accelerations. The idealized records are then analyzed with the EMD and EEMD methods and time-varying acceleration error estimates are obtained. Finally, the methods are applied to tide gauge observations from the Atlantic coast encompassing the hotspot region, and the acceleration estimates are interpreted in light of the results from the idealized data. Generally, EEMD provides more stable acceleration estimates that are less sensitive to the record start date than EMD. When the data record exceeds twice the ~67-year multidecadal oscillation period, the EEMD acceleration error falls to ~25% or less for idealized annual mean records with a quadratic trend. For records of intermediate length - between one and two multidecadal oscillation periods - the acceleration error is strongly time-varying. For data records shorter than ~67 years, the multidecadal oscillation is inadequately separated from the nonlinear trend and contributes

Sea-levelrise threatens coastal salt-marshes and mangrove forests around the world, and a key determinant of coastal wetland vulnerability is whether its surface elevation can keep pace with risingsealevel. Globally, a large data gap exists because wetland surface and shallow subsurface processes remain unaccounted for by traditional vulnerability assessments using tide gauges. Moreover, those processes vary substantially across wetlands, so modelling platforms require relevant local data. The low-cost, simple, high-precision rod surface-elevation table–marker horizon (RSET-MH) method fills this critical data gap, can be paired with spatial data sets and modelling and is financially and technically accessible to every country with coastal wetlands. Yet, RSET deployment has been limited to a few regions and purposes. A coordinated expansion of monitoring efforts, including development of regional networks that could support data sharing and collaboration, is crucial to adequately inform coastal climate change adaptation policy at several scales.

Using instrumental observations from the Permanent Service for Mean SeaLevel (PSMSL), we provide a new assessment of the global sea-levelacceleration for the last ~ 2 centuries (1820-2010). Our results, obtained by a stack of tide gauge time series, confirm the existence of a global sea-levelacceleration (GSLA) and, coherently with independent assessments so far, they point to a value close to 0.01 mm/yr2. However, differently from previous studies, we discuss how change points or abrupt inflections in individual sea-level time series have contributed to the GSLA. Our analysis, based on methods borrowed from econometrics, suggests the existence of two distinct driving mechanisms for the GSLA, both involving a minority of tide gauges globally. The first effectively implies a gradual increase in the rate of sea-levelrise at individual tide gauges, while the second is manifest through a sequence of catastrophic variations of the sea-level trend. These occurred intermittently since the end of the 19th century and became more frequent during the last four decades.

Most people, especially for Pacific Islanders, are aware of the sealevel change which may caused by many factors, but no of them has deeper sensation of flooding than Tuvaluan. Tuvalu, a coral country, consists of nine low-lying islands in the central Pacific between the latitudes of 5 and 10 degrees south, has the average elevation of 2 meters (South Pacific SeaLevel and Climate Monitoring Project, SPSLCMP report, 2006) up to sealevel. Meanwhile, the maximum sealevel recorded was 3.44m on February 28th 2006 that damaged Tuvaluan's property badly. Local people called the flooding water oozes up out of the ground "King Tide", that happened almost once or twice a year, which destroyed the plant, polluted their fresh water, and forced them to colonize to some other countries. The predictable but uncontrollable king tide had been observed for a long time by SPSLCMP, but some of the uncertainties which intensify the sealevelrise need to be analyzed furthermore. In this study, a span of 18 years of tide gauge data accessed from SeaLevel Fine Resolution Acoustic Measuring Equipment (SEAFRAME) are compared with the satellite altimeter data accessed from Archiving Validation and Interpretation of Satellite Data in Oceanography (AVISO). All above are processed under the limitation of same time and spatial range. The outcome revealed a 9.26cm difference between both. After the tide gauge data shifted to the same base as altimeter data, the results showed the unknown residuals are always positive under the circumstances of the sealevelrise above 3.2m. Apart from uncertainties in observing, the residual reflected unknown contributions. Among the total case number of sealevelrise above 3.2m is 23 times, 22 of which were recorded with oceanic warm eddy happened simultaneously. The unknown residual seems precisely matched with oceanic warm eddies and illustrates a clear future approach for Tuvaluan to care for.

EPA supports the development and maintenance of water utility infrastructure across the country. Included in this effort is helping the nation’s water utilities anticipate, plan for, and adapt to risks from flooding, sealevelrise, and storm surge.

One of the most certain consequences of global warming is an increase of global (eustatic) sealevel. The resulting inundation from rising seas will heavily impact low-lying areas; at least 100 million persons live within one meter of mean sealevel and are at increased risk in the coming decades. The very existence of some island states and deltaic coasts is threatened by sealevelrise. An additional threat affecting some of the most heavily developed and economically valuable real estate will come from an exacerbation of sandy beach erosion. As the beach is lost, fixed structures nearby are increasingly exposed to the direct impact of storm waves, and will ultimately be damaged or destroyed unless expensive protective measures are taken. It has long been speculated that the underlying rate of long-term sandy beach erosion is two orders of magnitude greater than the rate of rise of sealevel, so that any significant increase of sealevel has dire consequences for coastal inhabitants. We present an analysis of a large and consistent database of shoreline positions and sealevels to show that there is an underlying highly multiplicative relation of sandy beach erosion to sealevelrise. This result means that the already-severe coastal erosion problems witnessed in the 20th century will be exacerbated in the 21st century under plausible global warming scenarios.

A primary effect of global warming is acceleratedsealevelrise, which will eventually drown low-lying coastal areas, including some of the world's most populated cities. Predictions from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) suggest that sealevel may rise by as much as 0.6 meter by 2100 [Solomon et al., 2007]. However, uncertainty remains about how projected melting of the Greenland and Antarctic ice sheets will contribute to sealevelrise. Further, considerable variability is introduced to these calculations due to coastal subsidence, especially along the northern Gulf of Mexico (see http://tidesandcurrents.noaa.gov/sltrends/sltrends.shtml).

Global mean sealevel is rising in response to two primary factors: warming oceans and diminishing glaciers and ice sheets. If melted completely, glaciers would raise sealevels by half a meter, much less than that the 80 meters or so that would result from total melt of the massive Greenland and Antarctic ice sheets. That is why glacier contributions to sealevelrise have been less studied, allowing estimates of to vary widely. Glacier contributions to sealevel change are challenging to quantify as they are broadly distributed, located in remote and poorly accessible high latitude and high altitude regions, and ground observations are sparse. Advances in satellite altimetry (ICESat) and gravimetry (GRACE) have helped, but they also have their own challenges and limitations. Here we present an updated (2003-2014) synthesis of multiple techniques adapted for varying regions to show that rates of glacier loss change little between the 2003-2009 and 2003-2014 periods, accounting for roughly one third of global mean sealevelrise. Over the next century and beyond glaciers are expected to continue to contribute substantial volumes of water to the world's oceans, motivating continued study of how glaciers respond to climate change that will improve projections of future sealevels.

Increase of global sealevel is one of the potential consequences of climate change and represents a threat for the U.S.A coastal regions, which are highly populated and home of critical infrastructures. The potential danger caused by sealevelrise may escalate if sealevelrise is coupled with an increase in frequency and intensity of storms that may strike these regions. These coupled threats present a clear risk to population and critical infrastructure and are concerns for Federal, State, and particularly local response and recovery planners. Understanding the effect of sealevelrise on the risk to critical infrastructure is crucial for long planning and for mitigating potential damages. In this work we quantify how infrastructure vulnerability to a range of storms changes due to an increase of sealevel. Our study focuses on the Norfolk area of the U.S.A. We assess the direct damage of drinking water and wastewater facilities and the power sector caused by a distribution of synthetic hurricanes. In addition, our analysis estimates indirect consequences of these damages on population and economic activities accounting also for interdependencies across infrastructures. While projections unanimously indicate an increase in the rate of sealevelrise, the scientific community does not agree on the size of this rate. Our risk assessment accounts for this uncertainty simulating a distribution of sealevelrise for a specific climate scenario. Using our impact assessment results and assuming an increase of future hurricanes frequencies and intensities, we also estimate the expected benefits for critical infrastructure.

Looking Glass is an application on the iPhone that visualizes in 3-D future scenarios of sealevelrise, overlaid on live camera imagery in situ. Using a technology known as augmented reality, the app allows a layperson user to explore various scenarios of sealevelrise using a visual interface. Then the user can see, in an immersive, dynamic way, how those scenarios would affect a real place. The first part of the experience activates users' cognitive, quantitative thinking process, teaching them how global sealevelrise, tides and storm surge contribute to flooding; the second allows an emotional response to a striking visual depiction of possible future catastrophe. This project represents a partnership between a science journalist, MIT, and the Rhode Island School of Design, and the talk will touch on lessons this projects provides on structuring and executing such multidisciplinary efforts on future design projects.

Presentation by Cristina Milesi, First Author, NASA Ames Research Center, Moffett Field, CA at the "Meeting the Challenge of SeaLevelRise in Santa Clara County" on June 19, 2005 Santa Clara County, bordering with the southern portion of the San Francisco Bay, is highly vulnerable to flooding and to sealevelrise (SLR). In this presentation, the latest sealevelrise projections for the San Francisco Bay will be discussed in the context of extreme water height frequency and extent of flooding vulnerability. I will also present preliminary estimations of levee requirements and possible mitigation through tidal restoration of existing salt ponds. The examples will draw mainly from the work done by the NASA Climate Adaptation Science Investigators at NASA Ames.

The impact of sealevelrise on coastal properties depends critically on the human response to the threat, which in turn depends on several factors, including the immediacy of the risk, the magnitude of property value at risk, options for adapting to the threat and the cost of th...

Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sealevelrise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sealevelrise, and that process-based models predict survival under a wide range of future sealevel scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sealevelrise, and the potential for marshes to migrate inland.

Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sealevelrise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sealevelrise, and that process-based models predict survival under a wide range of future sealevel scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sealevelrise, and the potential for marshes to migrate inland.

In determining the risk lowland deltaic topography, as threatened by sealevelrise and land subsidence, a number of important processes must be evaluated. Sealevelrise is a global process but with local manifestations. Asian deltas have been experiencing higher rates of sealevelrise due to the steric impact on dynamic (ocean) topography. Other large scale geophysical impacts on relative sealevel at the local scale include the isostatic and flexural response to Holocene sealevel history, Holocene sediment loads, and in former ice sheet zones --- glacial rebound. Tectonism does play a role on relative sealevelrise, particularly in South America where the Eastern coastline, particularly Argentina, is rising relative to regional sealevels. Subsidence is impacted by both natural ground compaction, and accelerated compaction due to, for example, peat oxidation that often has a human driver (e.g. swamp reclammation). Subsidence is also impacted by the extraction of deeper deposits of petroleum and water. Rates of delta subsidence vary widely, depending on the magnitude of the anthropogenic driver, from a few mm/y to 100's of mm/y. Ground water withdrawal is the dominant reason behind much of the world's coastal subsidence, with important exceptions. On average subsidence rates (all causes) now contribute to local sealevel innundations at rates four times faster then sealevel is rising. New technologies, particularly InSAR and GPS methods, can often pin point the local cause (e.g. water withdrawl for agriculture versus for aquaculture). Subsurface soil or rock heterogeneity, and other very local geological patterns such as historical river pathways, also influence the temporal and spatial patterns associated with delta subsidence.

When "ITV News" ran an item that shocked the author, about risingsealevels that will have caused the entire evacuation of the islands by the end of this year, he began to wonder whether the Pacific Ocean is really rising as fast as this. The media reporting of such things can be a double-edged sword. On the one hand, it brought to the author's…

Recent studies identified the U.S. East Coast north of Cape Hatteras as a "hotspot" for acceleratedsea-levelrise (SLR), and the analysis presented here shows that the area is also a "hotspot for accelerated flooding." The duration of minor tidal flooding [defined as 0.3 m above MHHW (mean higher high water)] has accelerated in recent years for most coastal locations from the Gulf of Maine to Florida. The average increase in annual minor flooding duration was ˜20 h from the period before 1970 to 1971-1990, and ˜50 h from 1971-1990 to 1991-2013; spatial variations in acceleration of flooding resemble the spatial variations of acceleration in sealevel. The increase in minor flooding can be predicted from SLR and tidal range, but the frequency of extreme storm surge flooding events (0.9 m above MHHW) is less predictable, and affected by the North Atlantic Oscillations (NAO). The number of extreme storm surge events since 1960 oscillates with a period of ˜15 year and interannual variations in the number of storms are anticorrelated with the NAO index. With higher seas, there are also more flooding events that are unrelated to storm surges. For example, it is demonstrated that week-long flooding events in Norfolk, VA, are often related to periods of decrease in the Florida Current transport. The results indicate that previously reported connections between decadal variations in the Gulf Stream (GS) and coastal sealevel may also apply to short-term variations, so flood predictions may be improved if the GS influence is considered.

Subsurface fluid-pressure declines caused by pumping of groundwater or hydrocarbons can lead to aquifer-system compaction and consequent land subsidence. This subsidence can be rapid, as much as 30 cm per year in some instances, and large, totaling more than 13 m in extreme examples. Thus anthropogenic subsidence may be the dominant contributor to relative sea-levelrise in coastal environments where subsurface fluids are heavily exploited. Maximum observed rates of human-induced subsidence greatly exceed the rates of natural subsidence of unconsolidated sediments (~0.1–1 cm yr−1) and the estimated rates of ongoing global sea-levelrise (~0.3 cm yr−1).

Sixteen hurricanes have made landfall along the U.S. east and Gulf coasts over the past decade. For most of these storms, the USGS with our partners in NASA and the U.S. Army Corps of Engineers have flown before and after lidar missions to detect changes in beaches and dunes. The most dramatic changes occurred when the coasts were completely submerged in an inundation regime. Where this occurred locally, a new breach was cut, like during Hurricane Isabel in North Carolina. Where surge inundated an entire island, the sand was stripped off leaving marshy outcrops behind, like during Hurricane Katrina in Louisiana. Sealevelrise together with sand starvation and repeated hurricane impacts could increase the probabilities of inundation and degrade coasts more than sealevelrise alone.

The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of acceleratedsea-levelrise. Under similar rates of rapid sea-levelrise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence.

With its 3,100 miles of tidal shoreline and low-lying rural and urban lands, “The Free State” is one of the most vulnerable to sea-levelrise. Historically, Marylanders have long had to contend with rising water levels along its Chesapeake Bay and Atlantic Ocean and coastal bay shores. Shorelines eroded and low-relief lands and islands, some previously inhabited, were inundated. Prior to the 20th century, this was largely due to the slow sinking of the land since Earth’s crust is still adjusting to the melting of large masses of ice following the last glacial period. Over the 20th century, however, the rate of rise of the average level of tidal waters with respect to land, or relative sea-levelrise, has increased, at least partially as a result of global warming. Moreover, the scientific evidence is compelling that Earth’s climate will continue to warm and its oceans will rise even more rapidly. Recognizing the scientific consensus around global climate change, the contribution of human activities to it, and the vulnerability of Maryland’s people, property, public investments, and natural resources, Governor Martin O’Malley established the Maryland Commission on Climate Change on April 20, 2007. The Commission produced a Plan of Action that included a comprehensive climate change impact assessment, a greenhouse gas reduction strategy, and strategies for reducing Maryland’s vulnerability to climate change. The Plan has led to landmark legislation to reduce the state’s greenhouse gas emissions and a variety of state policies designed to reduce energy consumption and promote adaptation to climate change.

This paper seeks to quantify the impact of a1-m sea-levelrise on coastal wetlands in 86 developing countries and territories. It is found that approximately 68 % of coastal wetlands in these countries are at risk. A large percentage of this estimated loss is found in Europe and Central Asia, East Asia, and the Pacific, as well as in the Middle East and North Africa. A small number of countries will be severely affected. China and Vietnam(in East Asia and the Pacific), Libya and Egypt (in the Middle East and North Africa), and Romania and Ukraine (in Europe and Central Asia) will bear most losses. In economic terms, the loss of coastal wetlands is likely to exceed $703 million per year in 2000 US dollars.

The development and implementation of applied research programs that maximize stakeholder collaboration and utility is a well-documented struggle for funding agencies. In 2007, NOAA initiated multi-year stakeholder engagement process to develop a regional-scale, inter-disciplinary research project that resulted in a novel approach to accelerate the application of research results into management. This process culminated in a 2009 federal funding opportunity and resultant 6-year Ecological Effects of SeaLevelRise-Northern Gulf of Mexico (EESLR-NGOM) project focused on the dynamic integration of biological models (wetlands and oysters) with inundation and storm surge models at three National Estuarine Research Reserves in Florida, Alabama, and Mississippi. The project implemented a co-management approach between a traditional principle investigator (PI) and newly created applications co-PI that led a management advisory committee. Our goal was to provide the dedicated funding and infrastructure necessary to ensure the initial relevancy of the proposed project results, to guide ongoing research efforts, and to aid the efficient incorporation of key scientific results and tools into direct management application. As the project nears completion in 2016 and modeling applications reach maturity, this presentation will discuss the programmatic approach that resulted in EESLR-NGOM as well as an evaluation of nearly 6-years of collaborative science. This evaluation will focus on the funding agency perspective, with an emphasis on assessing the pros and cons of project implementation to establish lessons-learned for related collaborative science efforts. In addition, with increased attention in the Gulf of Mexico on projected sealevelrise impacts to coastal ecosystem restoration and management, a core benchmark for this evaluation will be the use of project models and tools by coastal managers and planners at local, state, and/or federal agencies.

Projections of global sea-levelrise into the future have become more pessimistic over the past five years or so. A global rise by more than one metre by the year 2100 is now widely accepted as a serious possibility if greenhouse gas emissions continue unabated. That is witnessed by the scientific assessments that were made since the last IPCC report was published in 2007. The Delta Commission of the Dutch government projected up to 1.10 m as a 'high-end' scenario (Vellinga et al 2009). The Scientific Committee on Antarctic Research (SCAR) projected up to 1.40 m (Scientific Committee on Antarctic Research 2009), and the Arctic Monitoring and Assessment Programme (AMAP) gives a range of 0.90-1.60 m in its 2011 report (Arctic Monitoring and Assessment Programme 2011). And recently the US Army Corps of Engineers recommends using a 'low', an 'intermediate' and a 'high' scenario for global sea-levelrise when planning civil works programmes, with the high one corresponding to a 1.50 m rise by 2100 (US Army Corps of Engineers 2011). This more pessimistic view is based on a number of observations, most importantly perhaps the fact that sealevel has been rising at least 50% faster in the past decades than projected by the IPCC (Rahmstorf et al 2007, IPCC 2007). Also, the rate of rise (averaged over two decades) has accelerated threefold, from around 1 mm yr-1 at the start of the 20th century to around 3 mm yr-1 over the past 20 years (Church and White 2006), and this rate increase closely correlates with global warming (Rahmstorf et al 2011). The IPCC projections, which assume almost no further acceleration in the 20th century, thus look less plausible. And finally the observed net mass loss of the two big continental ice sheets (Van den Broeke et al 2011) calls into question the assumption that ice accumulation in Antarctica would largely balance ice loss from Greenland in the course of further global warming (IPCC 2007). With such a serious sea-levelrise on the horizon

Analysis of the risks of sea-levelrise favours conventionally measured metrics such as the area of land that may be subsumed, the numbers of properties at risk, and the capital values of assets at risk. Despite this, it is clear that there exist many less material but no less important values at risk from sea-levelrise. This paper re-theorises these multifarious social values at risk from sea-levelrise, by explaining their diverse nature, and grounding them in the everyday practices of people living in coastal places. It is informed by a review and analysis of research on social values from within the fields of social impact assessment, human geography, psychology, decision analysis, and climate change adaptation. From this we propose that it is the ‘lived values’ of coastal places that are most at risk from sea-levelrise. We then offer a framework that groups these lived values into five types: those that are physiological in nature, and those that relate to issues of security, belonging, esteem, and self-actualisation. This framework of lived values at risk from sea-levelrise can guide empirical research investigating the social impacts of sea-levelrise, as well as the impacts of actions to adapt to sea-levelrise. It also offers a basis for identifying the distribution of related social outcomes across populations exposed to sea-levelrise or sea-levelrise policies.

Human consequences of sealevelrise in California coastal counties reflect increasing population densities. Populations of coastal counties potentially affected by sealevelrise are projected to increase from 26.2 million persons in 1990 to 63.3 million persons in 2040. Urbanization dominates Los Angeles and the South Coast and San Francisco Bay and Delta regions. California shoreline populations subject to potential disruption impacts of sealevelrise are increasing rapidly. Enhanced risk zones for sealevelrise are specified for the Oxnard Plain of Ventura County on the south coast of California. Four separate sealevelrise scenarios are considered: (1) low (sealevelrise only); (2) moderate (adding erosion); (3) high (adding erosion and storm surges); and (4) a maximum case, a 3 m enhanced risk zone. Population impacts are outlined for the 3 m zone. More serious impacts from storm surges are expected than from sealevelrise and erosion. Stakeholders who support or oppose policies which may expose populations to sealevelrise include energy, commercial, financial, industrial, public agency, private interest and governmental organizations. These organizations respond to extreme events from differing positions. Vested interests determine the degree of mitigation employed by stakeholders to defer impacts of sealevelrise.

Two important topics in current climate research are the global warming hiatus and the seesaw pattern of sealevelrise (SLR) in the Pacific Ocean. We use ocean temperature and sea-level observations along with CMIP5 climate modelling data to investigate the relationship between the warming hiatus and sea-level variability in the Pacific Ocean. We analyse ocean heat content (OHC) trend by basin and layer for the full record (1945-2012) as well as the hiatus period (1998-2012). The result confirms the importance of the Pacific for heat uptake during the hiatus. Notably, the subsurface layer of the Pacific shows significant increase in OHC during the hiatus and a strong east-west compensation. This is mainly responsible for and reflected by the seesaw pattern of the Pacific sealevel through thermosteric effect. The control simulations from 38 CMIP5 models indicate that the seesaw pattern of SLR in the Pacific is mainly a feature of decadal to multidecadal variability. Most CMIP5 models can capture this variability, especially in the Pacific Decadal Oscillation region (poleward of 20°N). The CMIP5 control runs show that during periods of negative trends of global temperatures (analogous to hiatus decades in a warming world), sealevel increases in the western Pacific and decreases in the eastern Pacific. The opposite is true during periods of positive temperature trend (accelerated warming). These results suggest that a possible flip of the Pacific SLR seesaw would imply a resumption of surface warming and a SLR acceleration along the U.S. West Coast.

Invertebrates in estuaries could be at a greater risk of parasitism as climate change causes sealevels to rise. A new paper published 8 December in Proceedings of the National Academy of Sciences of the United States of America (doi:10.1073/pnas.1416747111) describes how rapid sealevelrise in the Holocene affected the population of parasitic flatworms called trematodes.

The response of tidal marshes to increasing sea-levelrise is uncertain. Tidal marshes can adapt to risingsealevels through vertical accretion and inland migration. Yet tidal marshes are vulnerable to submergence if the rate of sea-levelrise exceeds the rate of accretion and if inland migration is limited by natural features or development. We studied how Piermont and Iona Island Marsh, two tidal marshes on the Hudson River, New York, would be affected by sea-levelrise of 0.5m, 1m, and 1.5m by 2100. This study was based on the 2011-2012 Coastal New York LiDAR survey. Using GIS we mapped sea-levelrise projections accounting for accretion rates and calculated the submerged area of the marsh. Based on the Hudson River National Estuarine Research Reserve Vegetation 2005 dataset, we studied how elevation zones based on vegetation distributions would change. To evaluate the potential for inland migration, we assessed land cover around each marsh using the National Land Cover Database 2011 Land Cover dataset and examined the slope beyond the marsh boundaries. With an accretion rate of 0.29cm/year and 0.5m of sea-levelrise by 2100, Piermont Marsh would be mostly unchanged. With 1.5m of sea-levelrise, 86% of Piermont Marsh would be flooded. For Iona Island Marsh with an accretion rate of 0.78cm/year, sea-levelrise of 0.5m by 2100 would result in a 4% expansion while 1.5m sea-levelrise would cause inundation of 17% of the marsh. The results indicate that Piermont and Iona Island Marsh may be able to survive rates of sea-levelrise such as 0.5m by 2100 through vertical accretion. At rates of sea-levelrise like 1.5m by 2100, vertical accretion cannot match sea-levelrise, submerging parts of the marshes. High elevations and steep slopes limit Piermont and Iona Island Marsh's ability to migrate inland. Understanding the impacts of sea-levelrise on Piermont and Iona Island Marsh allows for long-term planning and could motivate marsh conservation programs.

Tidal salt marsh is especially sensitive to deterioration due to the effects of acceleratedsealevelrise when combined with other anthropogenically linked stressors, including crab herbivory, changes in tidal hydrology, nutrient loading, dam construction, changes in temperature...

Vietnamese communities in the Mekong Delta are faced with the substantial impacts of risingsealevels and salinity intrusion. The construction of embankments and dykes has historically been the principal strategy of the Vietnamese government to mitigate the effects of salinity intrusion on agricultural production. A predicted sea-levelrise of 30 cm by the year 2050 is expected to accelerate salinity intrusion. This study combines hydrologic, agronomic and behavioural assessments to identify effective adaptation strategies reliant on land-use change (soft options) and investments in water infrastructure (hard options). As these strategies are managed within different policy portfolios, the political discussion has polarized between choices of either soft or hard options. This paper argues that an ensemble of hard and soft policies is likely to provide the most effective results for people's livelihoods in the Mekong Delta. The consequences of policy deliberations are likely to be felt beyond the Mekong Delta as levels of rice cultivation there also affect national and global food security.

SeaRISE (Sea-level Response to Ice Sheet Evolution) is a community organized modeling effort, whose goal is to inform the fifth IPCC of the potential sea-level contribution from the Greenland and Antarctic ice sheets in the 21st and 22nd century. SeaRISE seeks to determine the most likely ice sheet response to imposed climatic forcing by initializing an ensemble of models with common datasets and applying the same forcing to each model. Sensitivity experiments were designed to quantify the sea-levelrise associated with a change in: 1) surface mass balance, 2) basal lubrication, and 3) ocean induced basal melt. The range of responses, resulting from the multi-model approach, is interpreted as a proxy of uncertainty in our sea-level projections. http://websrv.cs .umt.edu/isis/index.php/SeaRISE_Assessment.

While there is scientific consensus that global and local mean sealevel (GMSL and LMSL) has risen since the late nineteenth century, the relative contribution of natural and anthropogenic forcing remains unclear. Here we provide a probabilistic upper range of long-term persistent natural GMSL/LMSL variability (P=0.99), which in turn, determines the minimum/maximum anthropogenic contribution since 1900. To account for different spectral characteristics of various contributing processes, we separate LMSL into two components: a slowly varying volumetric component and a more rapidly changing atmospheric component. We find that the persistence of slow natural volumetric changes is underestimated in records where transient atmospheric processes dominate the spectrum. This leads to a local underestimation of possible natural trends of up to ∼1 mm per year erroneously enhancing the significance of anthropogenic footprints. The GMSL, however, remains unaffected by such biases. On the basis of a model assessment of the separate components, we conclude that it is virtually certain (P=0.99) that at least 45% of the observed increase in GMSL is of anthropogenic origin. PMID:26220773

Sealevels are rising as a result of global warming, but assessing the rate of the rise is proving difficult. In his Perspective, Church highlights the report by Cabanes et al., who have reassessed observational data and find that it is closer to model estimates than previously found. However, observational data are still limited and models disagree in their regional projections. With present data and models, regional sea-level changes cannot be predicted with confidence.

Global climate change and concomitant risingsealevel will have a profound impact on Florida's coastal and marine systems. Sea-levelrise will increase erosion of beaches, cause saltwater intrusion into water supplies, inundate coastal marshes and other important habitats, and make coastal property more vulnerable to erosion and flooding. Yet most coastal areas are currently managed under the premise that sea-levelrise is not significant and the shorelines are static or can be fixed in place by engineering structures. The new reality of sea-levelrise and extreme weather due to climate change requires a new style of planning and management to protect resources and reduce risk to humans. Scientists must: (1) assess existing coastal vulnerability to address short term management issues and (2) model future landscape change and develop sustainable plans to address long term planning and management issues. Furthermore, this information must be effectively transferred to planners, managers, and elected officials to ensure their decisions are based upon the best available information. While there is still some uncertainty regarding the details of risingsealevel and climate change, development decisions are being made today which commit public and private investment in real estate and associated infrastructure. With a design life of 30 yrs to 75 yrs or more, many of these investments are on a collision course with risingsealevel and the resulting impacts will be significant. In the near term, the utilization of engineering structures may be required, but these are not sustainable and must ultimately yield to "managed withdrawal" programs if higher sea-level elevations or rates of rise are forthcoming. As an initial step towards successful adaptation, coastal management and planning documents (i.e., comprehensive plans) must be revised to include reference to climate change and risingsea-level.

Sea-levelrise famously poses an existential threat to island nations like Kiribati, Tuvalu and the Maldives. Yet as the global mean sea-levelrises, the response of any one location at any given time will depend on the natural variability in regional sea-level and other impact of local human activities on coastal processes. As with climate warming, the state of an individual shoreline or the extent of flooding on a given day is not proof of a sea-level trend, nor is a global sea-level trend a good predictor of individual flooding or erosion events. Failure to consider the effect of natural variability and local human activity on coastal processes often leads to misattribution of flooding events and even some long-term shoreline changes to global sealevelrise. Moreover, unverified attribution of individual events or changes to specific islets to sealevelrise can inflame or invite scepticism of the strong scientific evidence for an accelerating increase in the global sealevel due to the impacts of human activity on the climate system. This is particularly important in developing nations like Kiribati, which are depending on international financial support to adapt to risingsealevels. In this presentation, I use gauge data and examples from seven years of field work in Tarawa Atoll, the densely populated capital of Kiribati, to examine the complexity of local sealevel and shoreline change in one of the world's most vulnerable countries. First, I discuss how the combination of El Nino-driven variability in sea-level and the astronomical tidal cycle leads to flooding and erosion events which can be mistaken for evidence of sea-levelrise. Second, I show that human modification to shorelines has redirected sediment supply, leading, in some cases, to expansion of islets despite risingsealevels. Taken together, the analysis demonstrates the challenge of attributing particular coastal events to global mean sea-levelrise and the impact on decision-making. The

Synthesis and Assessment Product 4.1 will synthesize information from the ongoing mapping efforts by federal and non-federal researchers related to the implications of risingsealevel. It will overlay the various data layers to develop new results made possible by bringing together researchers that are otherwise working independently. Because of time, data, and resource limitations, the synthesis will focus on a contiguous portion of the U.S. coastal zone (New York to North Carolina). The report will also develop a plan for sealevelrise research to answer the questions that are most urgent for near-term decisionmaking. This report will address the implications of sealevelrise on three spatial scales by providing: • A literature review that puts the report within the nationwide context. • Data overlays and a state-of-the-art quantitative assessment concerning coastal elevations, shore erosion, and wetland accretion for a multi-state study area along the U.S. Atlantic Coast: New York to North Carolina. • Qualitative discussions and case studies that document in greater detail the impact of sealevelrise on smaller areas within the mid-Atlantic study area. This report will provide information that supports the specific goal in Chapter 9 of the Strategic Plan for the Climate Change Science Program (CCSP, 2003) to analyze how coastal environmental programs can be improved to adapt to sealevelrise while enhancing economic growth.

Coastal sealevelrise is one the most important potential environmental risks. Multiple satellite altimeters flying on the same repeat orbit track have allowed estimation of global mean sealevel for the past 20 years, and the time series has yielded information about the average rate of sealevel increase over that time. Due to the duration, consistency, and inter-calibration of the altimeter measurements, the time series is now considered a climate record. The time series has also shown the strong dependence of sealevel on interannual signals such as the ENSO and the NAO. But the most important sealevel effects of climate change will be felt on the regional and local scales. At these smaller scales, local effects due to topography, tides, earth deformation (glacial isostatic adjustment (GIA), subsidence, etc.), and storm surges must also be considered when estimating the risks of sealevel change to coastal communities. Recently, work has begun to understand the methods applicable to estimating the risks of expected sealevel change to coastal communities (Strauss et al., 2012; Tebaldi et al., 2012). Tebaldi et al (2012) merged the expected global mean sealevel increase from the semi-empirical model of Vermeer and Rahmstorf (2009) with historical local tide gauges to predict increases in storm surge risk posed by increasing sealevel. In this work, we will further explore the currently available data and tools that can potentially be used to provide a sealevel climate change indicator and local risk assessment along US coasts. These include global and regional sealevel trends from the satellite altimetry climate record, in situ tide gauge measurements and the historical extremes at each location, local tide and storm surge models, topographic surveys of vulnerable coastlines, GIA models, and measurements of local subsidence and crustal deformation rates. We will also evaluate methods to estimate the increased risk to communities from sealevel change

Assumptions of a static landscape inspire predictions that about half of the world's coastal wetlands will submerge during this century in response to sea-levelacceleration. In contrast, we use simulations from five numerical models to quantify the conditions under which ecogeomorphic feedbacks allow coastal wetlands to adapt to projected changes in sealevel. In contrast to previous sea-level assessments, we find that non-linear feedbacks among inundation, plant growth, organic matter accretion, and sediment deposition, allow marshes to survive conservative projections of sea-levelrise where suspended sediment concentrations are greater than ~20 mg/L. Under scenarios of more rapid sea-levelrise (e.g., those that include ice sheet melting), marshes will likely submerge near the end of the 21st century. Our results emphasize that in areas of rapid geomorphic change, predicting the response of ecosystems to climate change requires consideration of the ability of biological processes to modify their physical environment.

Sealevelrise resulting from climate change and land subsidence is expected to severely impact the duration and associated damage resulting from flooding events in tidal communities. These communities must continuously invest resources for the maintenance of existing structures and installation of new flood prevention infrastructure. Tide gates are a common flood prevention structure for low-lying communities in the tidal zone. Tide gates close during incoming tides to prevent inundation from downstream water propagating inland and open during outgoing tides to drain upland areas. Higher downstream mean sealevel elevations reduce the effectiveness of tide gates by impacting the hydraulics of the system. This project developed a HEC-RAS and HEC-HMS model of an existing tide gate structure and its upland drainage area in the New Jersey Meadowlands to simulate the impact of rising mean sealevel elevations on the tide gate's ability to prevent upstream flooding. Model predictions indicate that sealevelrise will reduce the tide gate effectiveness resulting in longer lasting and deeper flood events. The results indicate that there is a critical point in the sealevel elevation for this local area, beyond which flooding scenarios become dramatically worse and would have a significantly negative impact on the standard of living and ability to do business in one of the most densely populated areas of America.

In the high-salinity seaward portions of estuaries, oysters seek refuge from predation, competition and disease in intertidal areas, but this sanctuary will be lost if vertical reef accretion cannot keep pace with sea-levelrise (SLR). Oyster-reef abundance has already declined ~85% globally over the past 100 years, mainly from over harvesting, making any additional losses due to SLR cause for concern. Before any assessment of reef response to accelerated SLR can be made, direct measures of reef growth are necessary. Here, we present direct measurements of intertidal oyster-reef growth from cores and terrestrial lidar-derived digital elevation models. On the basis of our measurements collected within a mid-Atlantic estuary over a 15-year period, we developed a globally testable empirical model of intertidal oyster-reef accretion. We show that previous estimates of vertical reef growth, based on radiocarbon dates and bathymetric maps, may be greater than one order of magnitude too slow. The intertidal reefs we studied should be able to keep up with any future accelerated rate of SLR (ref. ) and may even benefit from the additional subaqueous space allowing extended vertical accretion.

Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sealevelrise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sealevelrise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sealevel will rise in the coming century (1990-2090) by 2.2-4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sealevelrise [Grinsted et al., 2009; Milne et al., 2009].

Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sealevelrise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sealevelrise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sealevel will rise in the coming century (1990–2090) by 2.2–4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sealevelrise [Grinsted et al., 2009; Milne et al., 2009].

Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sealevelrise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sealevelrise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sealevel will rise in the coming century (1990-2090) by 2.2-4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sealevelrise [Grinsted et al., 2009; Milne et al., 2009].

Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-levelrise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sealevel during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo-sealevel records.

The accumulation of soil organic matter (SOM) is an important mechanism for many tidal wetlands to keep pace with sea-levelrise. SOM accumulation is governed by the rates of production and decomposition of organic matter. While plant productivity responses to sea-levelrise are well understood, far less is known about the response of SOM decomposition to acceleratedsea-levelrise. Here we quantified the effects of sea-levelrise on SOM decomposition by exposing planted and unplanted tidal marsh monoliths to experimentally manipulated flood duration. The study was performed in a field-based mesocosm facility at the Smithsonian Global Change Research Wetland, a micro tidal brackish marsh in Maryland, US. SOM decomposition was quantified as CO2 efflux, with plant- and SOM-derived CO2 separated using a stable carbon isotope approach. Despite the dogma that decomposition rates are inversely related to flooding, SOM mineralization was not sensitive to varying flood duration over a 35 cm range in surface elevation in unplanted mesocoms. In the presence of plants, decomposition rates were strongly and positively related to aboveground biomass (p≤0.01, R2≥0.59). We conclude that rates of soil carbon loss through decomposition are driven by plant responses to sealevel in this intensively studied tidal marsh. If our result applies more generally to tidal wetlands, it has important implications for modeling carbon sequestration and marsh accretion in response to acceleratedsea-levelrise.

In the Thailand -EC GEO2TECDI-SONG Project we investigate the sealevel change and vertical land motion in Thailand. First, Bangkok is situated in river delta and average height is closed to sealevel. Second, it is subsiding due to ground water extraction. Third, it is experiencing post-seismic motion due to nearby mega thrust earthquakes and fourth, it suffers from rising of sealevels due to global climate change. This poses a serious threat on Thai society and economy. Before mitigation methods can be devised we aim at charting, qualifying and quantifying all contributing effects by the use of satellite altimetry, GNSS, InSAR techniques and combining results with the in situ observations like tide gauge and with geophysical modeling. Adding GPS based vertical land motion to the tide gauge sealevel registration reveals the absolute sealevel change, which is nicely confirmed by altimetry. We find an average absolute rise of 3.5 mm/yr + 0.7, but nears mouth of Chao Praya River (Bangkok) and the Mekong delta (Ho Chi Min City), this mounts to 4 to 5 mm/yr, faster than global average. This is reinforced when accounting for the tectonic subsidence that resulted from 2004 9.1Mw Sumatra/Andaman earthquake; from 2005 onwards we find downfall in the order of 10 mm/yr. RADARSAT InSAR analyses show subsidence rates up to 25 mm/yr at many places along coastal Bangkok.

The United States National Park Service (NPS) manages significant stretches of shoreline along the U.S. Atlantic, Pacific, and Gulf Coasts that are vulnerable to long-term sealevelrise, shoreline erosion, and storm impacts. These parks have a wide variety of missions— protecting some of the nation's most important natural and cultural resources. The parks must also provide visitor access and education requiring infrastructure such as roads, visitor centers, trails, and buildings for facilities management. Planning for the likely impacts from sealevelrise to both resources and infrastructure is a complex balancing act. Using coastal engineering to protect cultural resources or infrastructure may harm natural resources. At the same time, there are clearly some cultural and historical resources that are so critical that they must be protected. In an attempt to begin to attack this dilemma, the NPS Climate Change Response Program has initiated a sealevelrise adaptation study that will provide a first-order tally of the park assets at risk to sealevelrise and to begin to develop a plan for prioritizing those assets that must be protected, those that can be moved or abandoned, and an examination of how best to approach this without harming critical natural resources. This presentation will discuss the preliminary results of this effort along with several relevant case studies.

Global warming and the resulting melting of polar ice sheets could increase global sealevels significantly. Some studies have predicted mean sealevel increases in the order of six inches to one foot in the next 25 to 50 years. This could have severe irreversible impacts on low-lying areas of Florida's Everglades. The key objective of this study is to evaluate the effects of a one foot sealevelrise on Cape Sable Seaside Sparrow (CSSS) nesting areas within the Everglades National Park (ENP). A regional-scale hydrologic model is used to assess the sensitivities of this sea-levelrise scenario. Florida's Everglades supports a unique ecosystem. At present, about 50 percent of this unique ecosystem has been lost due to urbanization and farming. Today, the water flow in the remnant Everglades is also regulated to meet a variety of competing environmental, water-supply and flood-control needs. A 30-year, eight billion dollar (1999 estimate) project has been initiated to improve Everglades' water flows. The expected benefits of this restoration project will be short-lived if the predicted sealevelrise causes severe impacts on the environmentally sensitive areas of the Everglades. Florida's Everglades is home to many threatened and endangered species of wildlife. The Cape Sable Seaside Sparrow population in the ENP is one such species that is currently listed as endangered. Since these birds build their nests close to the ground surface (the base of the nest is approximately six inches from the ground surface), they are directly affected by any sealevel induced ponding depth, frequency or duration change. Therefore, the CSSS population serves as a good indicator species for evaluating the negative impacts of sealevelrise on the Everglades' ecosystem. The impact of sealevelrise on the CSSS habitat is evaluated using the Regional Simulation Model (RSM) developed by the South Florida Water Management District. The RSM is an implicit, finite-volume, continuous

In the 21st century, acceleratedsea-levelrise and continued coastal development are expected to greatly alter coastal landscapes across the globe. Historically, many coastal ecosystems have responded to sea-level fluctuations via horizontal and vertical movement on the landscape. However, anthropogenic activities, including urbanization and the construction of flood-prevention infrastructure, can produce barriers that impede ecosystem migration. Here we show where tidal saline wetlands have the potential to migrate landward along the northern Gulf of Mexico coast, one of the most sea-levelrise sensitive and wetland-rich regions of the world. Our findings can be used to identify migration corridors and develop sea-levelrise adaptation strategies to help ensure the continued availability of wetland-associated ecosystem goods and services.

Dramatic erosion has occurred on some beaches of the Nile Delta. This erosion is greatest at the tips of the Nile promontories, with shoreline retreat up to 60 m/yr. Studies of the Nile Delta coast have indicated wide values of local subsidence ranging from 0.4 to 5.0 mm/yr. The relationship between sealevelrise and shoreline retreat according to the "Bruun Rule" has been applied on the eroded stretches along the 275 km coast of the Nile Delta. The Bruun Rule was applied individually to 55 beach profile lines extending from Alexandria to 35 km east of Port Said. Projected future shoreline retreat is predicted using EPA sealevelrise expectations for scenarios of 0.5, 1.0, 1.5, and 2.0 m sealevelrise. The predicted lower and higher sealevelrise rates predicted by the EPA (5 mm and 30 mm/yr) would result in a 2 m rise in sea-level by the year 2400 or 2058, respectively. With these rise values, the coastal areas of the western part of Abu Quir Bay, the Lake Manzala and the western part of Tineh Bay might attain a maximum land loss of 1.7, 1.9 and 1.4 km, respectively. These regions appear to be the most vulnerable areas to sealevelrise. The first region of Lake Manzala area lies on low-lying topography and the more rapidly subsiding area of the delta, while the other areas lie on a land surface of about one meter below MSL (mean sealevel). The estimated shoreline retreat along the delta resulted from sealevelrise combined with other major factors of sediment deficiency and coastal processes could accelerate coastal erosion, inundate wetlands and lowlands, and increase the salinity of lagoons and aquifers.

Ice loss to the sea currently accounts for virtually all of the sea-levelrise that is not attributable to ocean warming, and about 60% of the ice loss is from glaciers and ice caps rather than from the two ice sheets. The contribution of these smaller glaciers has accelerated over the past decade, in part due to marked thinning and retreat of marine-terminating glaciers associated with a dynamic instability that is generally not considered in mass-balance and climate modeling. This acceleration of glacier melt may cause 0.1 to 0.25 meter of additional sea-levelrise by 2100.

Ice loss to the sea currently accounts for virtually all of the sea-levelrise that is not attributable to ocean warming, and about 60% of the ice loss is from glaciers and ice caps rather than from the two ice sheets. The contribution of these smaller glaciers has accelerated over the past decade, in part due to marked thinning and retreat of marine-terminating glaciers associated with a dynamic instability that is generally not considered in mass-balance and climate modeling. This acceleration of glacier melt may cause 0.1 to 0.25 meter of additional sea-levelrise by 2100.

It is now established that complex coastal systems with elements such as beaches, inlets, bays, and rivers adjust their morphologies according to time-varying balances in between the processes that control the exchange of sediment. Acceleratedsealevelrise introduces a major perturbation into the sediment-sharing systems. A modeling framework based on a new SL-PR model which is an advanced version of the aggregate-scale CST Model and the event-scale CMS-2D and CMS-Wave combination have been used to simulate the recent evolution of a portion of the Florida panhandle coast. This combination of models provides a method to evaluate coefficients in the aggregate-scale model that were previously treated as fitted parameters. That is, by carrying out simulations of a complex coastal system with runs of the event-scale model representing more than a year it is now possible to directly relate the coefficients in the large-scale SL-PR model to measureable physical parameters in the current and wave fields. This cross-scale modeling procedure has been used to simulate the shoreline evolution at the Santa Rosa Island, a long barrier which houses significant military infrastructure at the north Gulf Coast. The model has been used to simulate 137 years of measured shoreline change and to extend these to predictions of future rates of shoreline migration.

Estimating and accounting for twentieth-century global mean sealevel (GMSL) rise is critical to characterizing current and future human-induced sea-level change. Several previous analyses of tide gauge records--employing different methods to accommodate the spatial sparsity and temporal incompleteness of the data and to constrain the geometry of long-term sea-level change--have concluded that GMSL rose over the twentieth century at a mean rate of 1.6 to 1.9 millimetres per year. Efforts to account for this rate by summing estimates of individual contributions from glacier and ice-sheet mass loss, ocean thermal expansion, and changes in land water storage fall significantly short in the period before 1990. The failure to close the budget of GMSL during this period has led to suggestions that several contributions may have been systematically underestimated. However, the extent to which the limitations of tide gauge analyses have affected estimates of the GMSL rate of change is unclear. Here we revisit estimates of twentieth-century GMSL rise using probabilistic techniques and find a rate of GMSL rise from 1901 to 1990 of 1.2 ± 0.2 millimetres per year (90% confidence interval). Based on individual contributions tabulated in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, this estimate closes the twentieth-century sea-level budget. Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records.The increase in rate relative to the 1901-90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-levelrise.

The International Panel on Climate Change has identified coastal ecosystems as areas that will be disproportionally affected by climate change. Current sea-levelrise projections range widely with 0.57 to 1.9 meters increase in mea sealevel by 2100. The expected accelerated rate of sea-levelrise through the 21st century will put many coastal ecosystems at risk, especially those in topographically low-gradient areas. We assessed marsh accretion and plant community state changes through 2100 at 12 tidal salt marshes around San Francisco Bay estuary with a sea-levelrise response model. Detailed ground elevation, vegetation, and water level data were collected at all sites between 2008 and 2011 and used as model inputs. Sediment cores (taken by Callaway and others, 2012) at four sites around San Francisco Bay estuary were used to estimate accretion rates. A modification of the Callaway and others (1996) model, the Wetland Accretion Rate Model for Ecosystem Resilience (WARMER), was utilized to run sea-levelrise response models for all sites. With a mean sealevelrise of 1.24 m by 2100, WARMER projected that the vast majority, 95.8 percent (1,942 hectares), of marsh area in our study will lose marsh plant communities by 2100 and to transition to a relative elevation range consistent with mudflat habitat. Three marshes were projected to maintain marsh vegetation to 2100, but they only composed 4.2 percent (85 hectares) of the total marsh area surveyed.

Coastal Louisiana wetlands contain about 37% of the estuarine herbaceous marshes in the conterminous United States. The long-term stability of coastal wetlands is often a function of a wetland's ability to maintain elevation equilibrium with mean sealevel through processes such as primary production and sediment accretion. However, Louisiana has sustained more coastal wetland loss than all other states in the continental United States combined due to a combination of natural and anthropogenic factors, including sea-levelrise. This study investigates the potential impact of current and acceleratingsea-levelrise rates on key coastal wetland habitats in southeastern Louisiana using the SeaLevel Affecting Marshes Model (SLAMM). Model calibration was conducted using a 1956–2007 observation period and hindcasting results predicted 35% versus observed 39% total marsh loss. Multiple sea-level-rise scenarios were then simulated for the period of 2007–2100. Results indicate a range of potential wetland losses by 2100, from an additional 2,188.97 km2 (218,897 ha, 9% of the 2007 wetland area) under the lowest sea-level-rise scenario (0.34 m), to a potential loss of 5,875.27 km2 (587,527 ha, 24% of the 2007 wetland area) in the highest sea-level-rise scenario (1.9 m). Model results suggest that one area of particular concern is the potential vulnerability of the region's baldcypress-water tupelo (Taxodium distichum-Nyssa aquatica) swamp habitat, much of which is projected to become permanently flooded (affecting regeneration) under all modeled scenarios for sea-levelrise. These findings will aid in the development of ecosystem management plans that support the processes and conditions that result in sustainable coastal ecosystems.

The persistence of salt marshes in the landscape depends on their ability to accommodate risingsealevel and minimize additional flooding stress. We use sediment cores and water level data from 14 marshes in Connecticut and New York to evaluate how marsh accretion, mineral and organic accumulation, carbon storage, and hydroperiod have changed from 1900 to 2012. We observe a regional acceleration in marsh accretion beginning around 1940, although marsh accretion did not reach parity with sealevelrise for several additional decades. Despite a rise in marsh accretion from 1.0 mm yr-1 circa 1900 to 3.6 mm yr-1 at present, the marsh surface has lost elevation relative to tidal datums. Declining relative elevations have led to increased tidal flooding, particularly in high marsh settings. As flooding increased, organic matter accumulation accelerated at all marshes. Accelerating mineral deposition was only observed in areas of short-form Spartina alterniflora. Mineral and organic sediment accumulation co-limit accretion, but organic accumulation was the stronger limiting factor, suggesting that marsh response to sealevelrise in the region is sensitive to processes affecting rates of belowground production and decomposition. Marsh carbon storage over the period of study averaged 84 g C m-2 yr-1, increasing as accretion accelerated. If marshes remain spatially intact as sealevelsrise, these results suggest that marshes have the capacity to become even greater C sinks.

When President Nixon created the US Environmental Protection Agency (EPA) in 1970 he said the environment must be perceived as a single, interrelated system. We are nowhere close to achieving this vision. Jim Titus and his colleagues [1] highlight one example of where one set of regulations or permits may be in conflict with another and where regulations were crafted in the absence of understanding the cumulative impact of global warming. The issue here is how to deal with the impacts of climate change on sealevel and the latter's impact on wetland polices, clean water regulations, and ecosystem services. The Titus paper could also be called `The tripping points of sealevelrise'. Titus and his colleagues have looked at the impact of such sealevelrise on the east coast of the United States. Adaptive responses include costly large- scale investment in shore protection (e.g. dikes, sand replenishment) and/or ecosystem migration (retreat), where coastal ecosystems move inland. Shore protection is limited by available funds, while ecosystem migrations are limited by available land use. The driving factor is the high probability of sealevelrise due to climate change. Estimating sealevelrise is difficult because of local land and coastal dynamics including rising or falling land areas. It is estimated that sealevel could rise between 8 inches and 2 feet by the end of this century [2]. The extensive data analysis done by Titus et al of current land use is important because, as they observe, `property owners and land use agencies have generally not decided how they will respond to sealevelrise, nor have they prepared maps delineating where shore protection and retreat are likely'. This is the first of two `tripping points', namely the need for adaptive planning for a pending environmental challenge that will create economic and environment conflict among land owners, federal and state agencies, and businesses. One way to address this gap in adaptive management

Coastal wetlands are among the most productive ecosystems in the world. These wetlands at the land-ocean margin provide many direct benefits to humans, including habitat for commercially important fisheries and wildlife; storm protection; improved water quality through sediment, nutrient, and pollution removal; recreation; and aesthetic values. These valuable ecosystems will be highly vulnerable to the effects of the rapid rise in sealevel predicted to occur during the next century as a result of global warming.

Mangroves are among the most well described and widely studied wetland communities in the world. The greatest threats to mangrove persistence are deforestation and other anthropogenic disturbances that can compromise habitat stability and resilience to sea-levelrise. To persist, mangrove ecosystems must adjust to risingsealevel by building vertically or become submerged. Mangroves may directly or indirectly influence soil accretion processes through the production and accumulation of organic matter, as well as the trapping and retention of mineral sediment. In this review, we provide a general overview of research on mangrove elevation dynamics, emphasizing the role of the vegetation in maintaining soil surface elevations (i.e. position of the soil surface in the vertical plane). We summarize the primary ways in which mangroves may influence sediment accretion and vertical land development, for example, through root contributions to soil volume and upward expansion of the soil surface. We also examine how hydrological, geomorphological and climatic processes may interact with plant processes to influence mangrove capacity to keep pace with risingsealevel. We draw on a variety of studies to describe the important, and often under-appreciated, role that plants play in shaping the trajectory of an ecosystem undergoing change.

Data from two tide-gage networks in Louisiana and the northern Gulf of Mexico were analyzed to determine local and regional trends in relative sealevelrise. The US Army Corps of Engineers (USACE) maintains a network of 83 tide-gage stations throughout coastal Louisiana. Of these, 20 have records for two lunar nodal cycles or more, and some date back to 1933. The authors used the USACE data set to determine the local and regional character of relative sealevelrise in Louisiana. The National ocean Survey (NOS) maintains nine tide gage stations throughout the northern Gulf of Mexico in Texas, Louisiana, Mississippi, Alabama, and Florida. All of the records of these stations exceed two lunar nodal cycles, and some date back to 1908. The authors used the NOS data set to determine the character of relative sealevelrise throughout the northern Gulf of Mexico. This investigation updates and extends the previous systematic regional tide gage analysis (which covered 1908-1983) to 1988.

Mangroves are among the most well described and widely studied wetland communities in the world. The greatest threats to mangrove persistence are deforestation and other anthropogenic disturbances that can compromise habitat stability and resilience to sea-levelrise. To persist, mangrove ecosystems must adjust to risingsealevel by building vertically or become submerged. Mangroves may directly or indirectly influence soil accretion processes through the production and accumulation of organic matter, as well as the trapping and retention of mineral sediment. In this review, we provide a general overview of research on mangrove elevation dynamics, emphasizing the role of the vegetation in maintaining soil surface elevations (i.e. position of the soil surface in the vertical plane). We summarize the primary ways in which mangroves may influence sediment accretion and vertical land development, for example, through root contributions to soil volume and upward expansion of the soil surface. We also examine how hydrological, geomorphological and climatic processes may interact with plant processes to influence mangrove capacity to keep pace with risingsealevel. We draw on a variety of studies to describe the important, and often under-appreciated, role that plants play in shaping the trajectory of an ecosystem undergoing change.

Most of the coastal wetlands of the South Atlantic region of the United States are expected to diminish in size in response to increasing human population growth and accelerating rates of risingsealevel. after examination of the distribution of wetlands, elevation contours, estimates of surface slope, soil types, and peat deposits on the peninsula, current models were considered unsuited for wetlands of the Albemarle-Pamlico peninsula of North Carolina. Some unusual features of this peninsula are low elevation (56% of total area <1.5 m), extensive coverage by wetlands (53%) and hydric soils (90%), negligible slopes of the land surface, virtual absence of tides, and lack of abundant sources of sediment. In the process of reconstructing how past rises in sealevel most likely led to present conditions, it became apparent that vertical accretion of peat in situ is largely responsible for landscape features in areas where elevations are lowest. Were it not for these deposits, the land surface area of the peninsula would be decreasing relative to sealevel. This situation contrasts sharply with areas in the eastern United States fringed by tidal marshes, which are undergoing overland migration at a rate dictated by landward slope and the rate of risingsealevel. If the rate of sealevelriseaccelerates, it is doubtful if vertical accretion rates of peat can prevent submergence of extensive areas of wetlands in the Albemarle-Pamlico peninsula. Land use and drainage in the lowest elevations of the peninsula are currently being affected by sealevel. Future land management of the peninsula will be constrained by potential landscape changes as a result of risingsealevel. 28 refs., 6 figs., 5 tabs.

Increasing nutrients and acceleratedsealevelrise (SLR) can cause marsh loss in some coastal systems. Responses to nutrients and SLR are complex and vary with soil matrix, marsh elevation, sediment inputs, and hydroperiod. We describe field and greenhouse studies examining sing...

Risingsealevel poses critical ecological and economical consequences for the low-lying megadeltas of the world where dependent populations and agriculture are at risk. The Mekong Delta of Vietnam is one of many deltas that are especially vulnerable because much of the land surface is below mean sealevel and because there is a lack of coastal barrier protection. Food security related to rice and shrimp farming in the Mekong Delta is currently under threat from saltwater intrusion, relative sealevelrise, and storm surge potential. Understanding the degree of potential change in sealevel under climate change is needed to undertake regional assessments of potential impacts and to formulate adaptation strategies. This report provides constructed time series of potential sealevelrise scenarios for the Mekong Delta region by incorporating (1) aspects of observed intra- and inter-annual sealevel variability from tide records and (2) projected estimates for different rates of regional subsidence and accelerated eustacy through the year 2100 corresponding with the Intergovernmental Panel on Climate Change (IPCC) climate models and emission scenarios.

Salt marsh ecosystems are maintained by the dominant macrophytes that regulate the elevation of their habitat within a narrow portion of the intertidal zone by accumulating organic matter and trapping inorganic sediment. The long-term stability of these ecosystems is explained by interactions among sealevel, land elevation, primary production, and sediment accretion that regulate the elevation of the sediment surface toward an equilibrium with mean sealevel. We show here in a salt marsh that this equilibrium is adjusted upward by increased production of the salt marsh macrophyte Spartina alterniflora and downward by an increasing rate of relative sea-levelrise (RSLR). Adjustments in marsh surface elevation are slow in comparison to interannual anomalies and long-period cycles of sealevel, and this lag in sediment elevation results in significant variation in annual primary productivity. We describe a theoretical model that predicts that the system will be stable against changes in relative mean sealevel when surface elevation is greater than what is optimal for primary production. When surface elevation is less than optimal, the system will be unstable. The model predicts that there is an optimal rate of RSLR at which the equilibrium elevation and depth of tidal flooding will be optimal for plant growth. However, the optimal rate of RSLR also represents an upper limit because at higher rates of RSLR the plant community cannot sustain an elevation that is within its range of tolerance. For estuaries with high sediment loading, such as those on the southeast coast of the United States, the limiting rate of RSLR was predicted to be at most 1.2 cm/yr, which is 3.5 times greater than the current, long-term rate of RSLR.

Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions, related primarily to elevation and hydroperiod, influence mangrove distributions; this review considers how these distributions change over time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks, and tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas measurements made using surface elevation tables and marker horizons provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-levelrise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-levelrise. However, many human pressures threaten mangroves, resulting in a continuing decline in their extent throughout the tropics.

Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions, related primarily to elevation and hydroperiod, influence mangrove distributions; this review considers how these distributions change over time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks, and tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas measurements made using surface elevation tables and marker horizons provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-levelrise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-levelrise. However, many human pressures threaten mangroves, resulting in a continuing decline in their extent throughout the tropics. *

Melting mountain glaciers and ice caps (MG&IC) are the second largest contributor to risingsealevel after thermal expansion of the oceans and are likely to remain the dominant glaciological contributor to risingsealevel in the 21st century. The aim of this work is to project 21st century volume changes of all MG&IC and to provide systematic analysis of uncertainties originating from different sources in the calculation. I provide an ensemble of 21st century volume projections for all MG&IC from the World Glacier Inventory by modeling the surface mass balance coupled with volume-area-length scaling and forced with temperature and precipitation scenarios from four Global Climate Models (GCMs). By upscaling the volume projections through a regionally differentiated approach to all MG&IC outside Greenland and Antarctica (514,380 km 2) I estimated total volume loss for the time period 2001-2100 to range from 0.039 to 0.150 m sealevel equivalent. While three GCMs agree that Alaskan glaciers are the main contributors to the projected sealevelrise, one GCM projected the largest total volume loss mainly due to Arctic MG&IC. The uncertainties in the projections are addressed by a series of sensitivity tests applied in the methodology for assessment of global volume changes and on individual case studies for particular glaciers. Special emphasis is put on the uncertainties in volume-area scaling. For both, individual and global assessments of volume changes, the choice of GCM forcing glacier models is shown to be the largest source of quantified uncertainties in the projections. Another major source of uncertainty is the temperature forcing in the mass balance model depending on the quality of climate reanalysis products (ERA-40) in order to simulate the local temperatures on a mountain glacier or ice cap. Other uncertainties in the methods are associated with volume-area-length scaling as a tool for deriving glacier initial volumes and glacier geometry changes in the

Against a background of climate change, Macau is very exposed to sealevelrise (SLR) because of its low elevation, small size, and ongoing land reclamation. Therefore, we evaluate sealevel changes in Macau, both historical and, especially, possible future scenarios, aiming to provide knowledge and a framework to help accommodate and protect against future SLR. Sealevel in Macau is now rising at an accelerated rate: 1.35 mm yr-1 over 1925-2010 and jumping to 4.2 mm yr-1 over 1970-2010, which outpaces the rise in global mean sealevel. In addition, vertical land movement in Macau contributes little to local sealevel change. In the future, the rate of SLR in Macau will be about 20% higher than the global average, as a consequence of a greater local warming tendency and strengthened northward winds. Specifically, the sealevel is projected to rise 8-12, 22-51 and 35-118 cm by 2020, 2060 and 2100, respectively, depending on the emissions scenario and climate sensitivity. Under the +8.5 W m-2 Representative Concentration Pathway (RCP8.5) scenario the increase in sealevel by 2100 will reach 65-118 cm—double that under RCP2.6. Moreover, the SLR will accelerate under RCP6.0 and RCP8.5, while remaining at a moderate and steady rate under RCP4.5 and RCP2.6. The key source of uncertainty stems from the emissions scenario and climate sensitivity, among which the discrepancies in SLR are small during the first half of the 21st century but begin to diverge thereafter.

A combination of natural and human factors are driving coastal change and making coastal regions and populations increasingly vulnerable. Sealevel, a major agent of coastal erosion, has varied greatly from -120 m below present during glacial period low-stands to + 4 to 6 m above present during interglacial warm periods. Geologic and tide gauge data show that global sealevel has risen about 12 to 15 cm during the past century with satellite measurements indicating an acceleration since the early 1990s due to thermal expansion and ice-sheet melting. Land subsidence due to tectonic forces and sediment compaction in regions like the mid-Atlantic and Louisiana increase the rate of relative sea-levelrise to 40 cm to 100 cm per century. Sea- levelrise is predicted to accelerate significantly in the near future due to climate change, resulting in pervasive impacts to coastal regions and putting populations increasingly at risk. The full implications of climate change for coastal systems need to be understood better and long-term plans are needed to manage coasts in order to protect natural resources and mitigate the effects of sea-levelrise and increased storms on human infrastructure. Copyright ASCE 2008.

Tidal habitats host a diversity of species and provide hydrological services such as shoreline protection and nutrient attenuation. Accretion of sediment and biomass enables tidal marshes and swamps to grow vertically, providing a degree of resilience to risingsealevels. Even if acceleratingsealevelrise overcomes this vertical resilience, tidal habitats have the potential to migrate inland as they continue to occupy land that falls within the new tide range elevations. The existence of developed land inland of tidal habitats, however, may prevent this migration as efforts are often made to dyke and protect developments. To test the importance of inland migration to maintaining tidal habitat abundance under a range of potential rates of sealevelrise, we developed a spatially explicit elevation tracking and habitat switching model, dubbed the Marsh Accretion and Inundation Model (MAIM), which incorporates elevation-dependent net land surface elevation gain functions. We applied the model to the metropolitan Washington, DC region, finding that the abundance of small National Park Service units and other public open space along the tidal Potomac River system provides a refuge to which tidal habitats may retreat to maintain total habitat area even under moderate sealevelrise scenarios (0.7 m and 1.1 m rise by 2100). Under a severe sealevelrise scenario associated with ice sheet collapse (1.7 m by 2100) habitat area is maintained only if no development is protected from rising water. If all existing development is protected, then 5%, 10%, and 40% of the total tidal habitat area is lost by 2100 for the three sealevelrise scenarios tested. PMID:27788209

Tidal habitats host a diversity of species and provide hydrological services such as shoreline protection and nutrient attenuation. Accretion of sediment and biomass enables tidal marshes and swamps to grow vertically, providing a degree of resilience to risingsealevels. Even if acceleratingsealevelrise overcomes this vertical resilience, tidal habitats have the potential to migrate inland as they continue to occupy land that falls within the new tide range elevations. The existence of developed land inland of tidal habitats, however, may prevent this migration as efforts are often made to dyke and protect developments. To test the importance of inland migration to maintaining tidal habitat abundance under a range of potential rates of sealevelrise, we developed a spatially explicit elevation tracking and habitat switching model, dubbed the Marsh Accretion and Inundation Model (MAIM), which incorporates elevation-dependent net land surface elevation gain functions. We applied the model to the metropolitan Washington, DC region, finding that the abundance of small National Park Service units and other public open space along the tidal Potomac River system provides a refuge to which tidal habitats may retreat to maintain total habitat area even under moderate sealevelrise scenarios (0.7 m and 1.1 m rise by 2100). Under a severe sealevelrise scenario associated with ice sheet collapse (1.7 m by 2100) habitat area is maintained only if no development is protected from rising water. If all existing development is protected, then 5%, 10%, and 40% of the total tidal habitat area is lost by 2100 for the three sealevelrise scenarios tested.

The potential for acceleratedsea-levelrise under anthropogenic warming is a significant societal problem, in particular in world's coastal deltaic regions where about half of the world's population resides. Quantifying geophysical sources of sea-levelrise with the goal of improved projection at local scales remains a complex and challenging interdisciplinary research problem. These processes include ice-sheet/glacier ablations, steric sea-level, solid Earth uplift or subsidence due to GIA, tectonics, sediment loading or anthropogenic causes, hydrologic imbalance, and human processes including water retention in reservoirs and aquifer extraction. The 2013 IPCC AR5 concluded that the observed and explained geophysical causes of global geocentric sea-levelrise, 1993-2010, is closer towards closure. However, the discrepancy reveals that circa 1.3→37.5% of the observed sea-levelrise remains unexplained. This relatively large discrepancy is primarily attributable to the wide range of estimates of respective contributions of Greenland and Antarctic ice-sheets and mountain/peripheral glaciers to sea-levelrise. Understanding and quantifying the natural and anthropogenic processes governing solid Earth (land, islands and sea-floor) uplift or subsidence at the regional and local scales remain elusive to enable addressing coastal vulnerability due to relative sea-levelrise hazards, such as the Bangladesh Delta. This study focuses on addressing coastal vulnerability of Bangladesh, a Belmont Forum/IGFA project, BanD-AID (http://Belmont-SeaLevel.org). Sea-levelrise, along with tectonic, sediment load and groundwater extraction induced land uplift/subsidence, have exacerbated Bangladesh's coastal vulnerability, affecting 150 million people in one of the world's most densely populated regions. Here we present preliminary results using space geodetic observations, including satellite radar and laser altimetry, GRACE gravity, tide gauge, hydrographic, and GPS/InSAR observed

Elevated CO2 and nitrogen (N) addition directly affect plant productivity and the mechanisms that allow tidal marshes to maintain a constant elevation relative to sealevel, but it remains unknown how these global change drivers modify marsh plant response to sealevelrise. Here we manipulated factorial combinations of CO2 concentration (two levels), N availability (two levels) and relative sealevel (six levels) using in situ mesocosms containing a tidal marsh community composed of a sedge, Schoenoplectus americanus, and a grass, Spartina patens. Our objective is to determine, if elevated CO2 and N alter the growth and persistence of these plants in coastal ecosystems facing risingsealevels. After two growing seasons, we found that N addition enhanced plant growth particularly at sealevels where plants were most stressed by flooding (114% stimulation in the + 10 cm treatment), and N effects were generally larger in combination with elevated CO2 (288% stimulation). N fertilization shifted the optimal productivity of S. patens to a higher sealevel, but did not confer S. patens an enhanced ability to tolerate sealevelrise. S. americanus responded strongly to N only in the higher sealevel treatments that excluded S. patens. Interestingly, addition of N, which has been suggested to accelerate marsh loss, may afford some marsh plants, such as the widespread sedge, S. americanus, the enhanced ability to tolerate inundation. However, if chronic N pollution reduces the availability of propagules of S. americanus or other flood-tolerant species on the landscape scale, this shift in species dominance could render tidal marshes more susceptible to marsh collapse.

Secular sealevel variations in the Mediterranean Sea are the result of a number of processes characterized by distinct time scales and spatial patterns. Here we predict the future sealevel variations in the Mediterranean Sea to year 2050 combining the contributions from terrestrial ice melt (TIM), glacial isostatic adjustment (GIA), and the ocean response (OR) that includes the thermal expansion and the ocean circulation contributions. The three contributions are characterized by comparable magnitudes but distinctly different sea-level fingerprints across the Mediterranean basin. The TIM component of future sea-levelrise is taken from Spada et al. (2013) and it is mainly driven by the melt of small glaciers and ice caps and by the dynamic ice loss from Antarctica. The sea-level fingerprint associated with GIA is studied using two distinct models available from the literature: ICE-5G(VM2) (Peltier, 2004) and the ice model progressively developed at the Research School of Earth Sciences (RSES) of the National Australian University (KL05) (see Fleming and Lambeck, 2004 and references therein). Both the GIA and the TIM sea-level predictions have been obtained with the aid of the SELEN program (Spada and Stocchi, 2007). The spatially-averaged OR component, which includes thermosteric and halosteric sea-level variations, recently obtained using a regional coupled ocean-atmosphere model (Carillo et al., 2012), vary between 2 and 7 cm according to scenarios adopted (EA1B and EA1B2, see Meehl at al., 2007). Since the sea-level variations associated with TIM mainly result from the gravitational interactions between the cryosphere components, the oceans and the solid Earth, and long-wavelength rotational variations, they are characterized by a very smooth global pattern and by a marked zonal symmetry reflecting the dipole geometry of the ice sources. Since the Mediterranean Sea is located in the intermediate far-field of major ice sources, TIM sea-level changes have sub

Geoengineering has been proposed as a feasible way of mitigating anthropogenic climate change, especially increasing global temperatures in the 21st century. The two main geoengineering options are limiting incoming solar radiation, or modifying the carbon cycle. Here we examine the impact of five geoengineering approaches on sealevel; SO(2) aerosol injection into the stratosphere, mirrors in space, afforestation, biochar, and bioenergy with carbon sequestration. Sealevel responds mainly at centennial time scales to temperature change, and has been largely driven by anthropogenic forcing since 1850. Making use a model of sea-levelrise as a function of time-varying climate forcing factors (solar radiation, volcanism, and greenhouse gas emissions) we find that sea-levelrise by 2100 will likely be 30 cm higher than 2000 levels despite all but the most aggressive geoengineering under all except the most stringent greenhouse gas emissions scenarios. The least risky and most desirable way of limiting sea-levelrise is bioenergy with carbon sequestration. However aerosol injection or a space mirror system reducing insolation at an accelerating rate of 1 W m(-2) per decade from now to 2100 could limit or reduce sealevels. Aerosol injection delivering a constant 4 W m(-2) reduction in radiative forcing (similar to a 1991 Pinatubo eruption every 18 months) could delay sea-levelrise by 40-80 years. Aerosol injection appears to fail cost-benefit analysis unless it can be maintained continuously, and damage caused by the climate response to the aerosols is less than about 0.6% Global World Product.

Geoengineering has been proposed as a feasible way of mitigating anthropogenic climate change, especially increasing global temperatures in the 21st century. The two main geoengineering options are limiting incoming solar radiation, or modifying the carbon cycle. Here we examine the impact of five geoengineering approaches on sealevel; SO2 aerosol injection into the stratosphere, mirrors in space, afforestation, biochar, and bioenergy with carbon sequestration. Sealevel responds mainly at centennial time scales to temperature change, and has been largely driven by anthropogenic forcing since 1850. Making use a model of sea-levelrise as a function of time-varying climate forcing factors (solar radiation, volcanism, and greenhouse gas emissions) we find that sea-levelrise by 2100 will likely be 30 cm higher than 2000 levels despite all but the most aggressive geoengineering under all except the most stringent greenhouse gas emissions scenarios. The least risky and most desirable way of limiting sea-levelrise is bioenergy with carbon sequestration. However aerosol injection or a space mirror system reducing insolation at an accelerating rate of 1 W m-2 per decade from now to 2100 could limit or reduce sealevels. Aerosol injection delivering a constant 4 W m-2 reduction in radiative forcing (similar to a 1991 Pinatubo eruption every 18 months) could delay sea-levelrise by 40–80 years. Aerosol injection appears to fail cost-benefit analysis unless it can be maintained continuously, and damage caused by the climate response to the aerosols is less than about 0.6% Global World Product. PMID:20798055

The vast body of contemporary climate change science is largely underpinned by the premise of a measured acceleration from anthropogenic forcings evident in key climate change proxies -- greenhouse gas emissions, temperature, and mean sealevel. By virtue, over recent years, the issue of whether or not there is a measurable acceleration in global mean sealevel has resulted in fierce, widespread professional, social, and political debate. Attempts to measure acceleration in global mean sealevel (GMSL) have often used comparatively crude analysis techniques providing little temporal instruction on these key questions. This work proposes improved techniques to measure real-time velocity and acceleration based on five GMSL reconstructions spanning the time frame from 1807 to 2014 with substantially improved temporal resolution. While this analysis highlights key differences between the respective reconstructions, there is now more robust, convincing evidence of recent acceleration in the trend of GMSL.

Atoll island is formed and maintained by sand production, transportation and sedimentation process. Major component of sand in the Pacific atolls is foraminifera, which is produced on the ocean-side reef flat, and then transported from the ocean-side to the lagoon-side coast through channels between the islands. Sand is then transported along the lagoon-side coast by longshore current, and finally deposited to nourish sandy beach. At present, however, this natural process has been deteriorated by local human stresses. High production of foraminifera and corals are degraded by human waste. Transportation of sand from the ocean to the lagoon is blocked by a causeway, and longshore transportation and sedimentation along the lagoon coast is prevented by jetties, dredges and upright seawalls. All these local factors severely reduce natural resilience and increase vulnerability against the projected future sealevelrise and the global changes. Countermeasure plans must be based on and must not conflict with the natural island formation process. We launched "Eco-technological management of Tuvalu against sealevelrise" under Science and Technology Research Partnership for Sustainable Development funded by JICA and JST. The goal of this project is to regenerate sandy beach along Fongafale Island, Funrafuti Atoll Tuvalu by rehabilitation of production, transportation and sedimentation process including establishing foraminifera culture system.; Fig. 1 Aerial view of Fongafale Is., Funafuti Atoll, Tuvalu.

In Bavaria the curriculum of the upper grade of high school includes a so called project seminar, running over one and a half year. The aims of the seminar are to let the pupils learn to work on a specific topic, to organize themselves in a team, to improve their soft skills and become familiar with the working life. The topic of the project seminar, jointly organized by the Bertold-Brecht-Gymnasium in Munich and the Deutsche Geodätische Forschungsinstitut (DGFI) was on the "Global sealevelrise". A team of 13 pupils computed the mean sealevelrise by using on the one hand altimetry data of TOPEX, Jason-1 and Jason2 and on the other hand data of globally distributed tide gauges, corrected for vertical crustal movements derived from GPS products. The results of the two independent approaches were compared with each other and discussed considering also statements and discussions found in press, TV, and the web. Finally, a presentation was prepared and presented at school.

The differential vulnerability of the conterminous United States to future sealevelrise from greenhouse climate warming is assessed, using a coastal hazards data base. This data contains information on seven variables relating to inundation and erosion risks. High risk shorelines are characterized by low relief, erodible substrate, subsidence, shoreline retreat, and high wave/tide energies. Very high risk shorelines on the Atlantic Coast (Coastal Vulnerability Index {ge}33.0) include the outer coast of the Delmarva Peninsula, northern Cape Hatteras, and segments of New Jersey, Georgia and South Carolina. Louisiana and sections of Texas are potentially the most vulnerable, due to anomalously high relative sealevelrise and erosion, coupled with low elevation and mobile sediments. Although the Pacific Coast is generally the least vulnerable, because of its rugged relief and erosion-resistant substrate, the high geographic variability leads to several exceptions, such as the San Joaquin-Sacramento Delta area, the barrier beaches of Oregon and Washington, and parts of the Puget Sound Lowlands. 31 refs., 2 figs., 3 tabs.

Sealevel, which has risen by 10 to 20 cm (4 to 8 inches) in the past century along most of the US coastline, is projected to rise an additional 48 cm (19 inches) by 2100, with a possible range of 13 cm to 95 cm (26 to 37 inches). Eustatic increases in sealevel are being caused largely by melting glaciers and ice sheets on land, and thermal expansion of ocean water. Sealevelrise will continue to accelerate beyond 2100 as a result of the great amount of time needed for oceans and ice sheets to approach equilibrium under the long-term perturbations anticipated with climate change. Tropical storms, hurricanes, typhoons, and similar extreme atmospheric phenomena along the southeastern coast of the US generate high winds that in turn create large waves and currents. Resulting storm surges can temporarily raise water levels by as much as 23 feet (7 meters) above normal. Although these events are sporadic, they are a primary cause of scour at bridges along most of the US coastline. Even if storm magnitudes and frequencies do not change as a result of global warming, an important impact of future storms, whether tropical or extratropical, will be their superposition on a risingsealevel. Thus sea-levelrise will increase impacts to the coast by a storm of a given magnitude by increasing the baseline water level for extreme storms. Because many coastal bridges were designed to withstand erosion produced by storm surges having 1 percent annual chance of occurrence (that is, 100-year storm surge), as sealevels increase the statistics used to design these structures changes. For example, a 50-year storm surge following an increase in sealevel could scour a bridge as severely as would the current 100-year storm surge. Impacts of risingsealevels on scour at coastal bridges in the southeastern US are illustrated by an analysis of the Cape Fear River estuary system in North Carolina. A numerical model of fully-coupled flow and sediment transport in open channels was used

We review and synthesize the geologic record that constrains the sources of sealevelrise and freshwater discharge to the global oceans associated with retreat of ice sheets during the last deglaciation. The Last Glacial Maximum (˜26-19 ka) was terminated by a rapid 5-10 m sealevelrise at 19.0-19.5 ka, sourced largely from Northern Hemisphere ice sheet retreat in response to high northern latitude insolation forcing. Sealevelrise of 8-20 m from ˜19 to 14.5 ka can be attributed to continued retreat of the Laurentide and Eurasian Ice Sheets, with an additional freshwater forcing of uncertain amount delivered by Heinrich event 1. The source of the abrupt acceleration in sealevelrise at ˜14.6 ka (meltwater pulse 1A, ˜14-15 m) includes contributions of 6.5-10 m from Northern Hemisphere ice sheets, of which 2-7 m represents an excess contribution above that derived from ongoing ice sheet retreat. Widespread retreat of Antarctic ice sheets began at 14.0-15.0 ka, which, together with geophysical modeling of far-field sealevel records, suggests an Antarctic contribution to this meltwater pulse as well. The cause of the subsequent Younger Dryas cold event can be attributed to eastward freshwater runoff from the Lake Agassiz basin to the St. Lawrence estuary that agrees with existing Lake Agassiz outlet radiocarbon dates. Much of the early Holocene sealevelrise can be explained by Laurentide and Scandinavian Ice Sheet retreat, with collapse of Laurentide ice over Hudson Bay and drainage of Lake Agassiz basin runoff at ˜8.4-8.2 ka to the Labrador Sea causing the 8.2 ka event.

It is well established that one consequence of increasing global sealevel is that the frequency of flooding at low-lying coastal sites will increase. We review recent evidence that the effects coastal geometry will create substantial spatial variations in the changes in flooding frequency with scales of order 100km. Using a simple model of the evolution of coastal property values we demonstrate that a consequence of sealevelrise is that the appreciation of coastal properties will peak, and then decline relative to higher properties. The time when the value reach a maximum is shown to depend upon the demand for the coastal property, and the local rate of change of flooding frequency due to sealevelrise. The simple model is then extended to include, in an elementary manner, the effects on the value of adjacent but higher properties. We show that the effect of increased flooding frequency of the lower properties leads to an accelerated appreciation of the value of upland properties and an accelerated decline in the value of the coastal properties. We then provide some example calculations for selected sites. We conclude with a discussion of comparisons of the prediction of the analyses to recent data, and then comments on the impact of sealevelrise on tax base of coastal communities.

Historic tidal records indicate that mean sealevel in San Francisco Bay has risen at a rate of about 2 mm/yr over the past 100 years. Over the past 20 years, the annual rate has accelerated to about 3 mm/yr. Recent climate change studies related to greenhouse gas emissions indicate that sealevels could rise much faster than even this rate, which would have a significant effect on coastal communities. Several communities in the San Francisco Bay area, which were not mapped to be within a flood zone by FEMA, are now prone to flooding due to risingsealevels. There is a significant amount of uncertainty associated with quantifying the rate of sealevel change because climate change science is still evolving and feedback loops such as temperature-ice melt, temperature-sealevels, and CO2-temperature are still under investigation. Therefore, the traditional engineering approach to solving a problem, which includes defining the problem, assessing existing conditions, analyzing data, and developing solutions is difficult when addressing climate change induced sealevel change. This paper describes work completed for two major proposed communities in the City of San Francisco. Peer-reviewed literature included the body of work by the Intergovernmental Panel on Climate Change, US federal and state agencies, and scientific papers by academia. Rates of sealevelrise were statistically analyzed using the end values and start or end rates specified in the studies. Probabilistic analyses of extreme values using Generalized Extreme Value Distributions (GEVD) and the Maximum Likelihood Approach were completed to develop extreme values for water levels including the effects of astronomical tides, storm events, ocean swell events, and tsunami events. These values were subsequently combined with sealevelrise estimates, and various scenarios of required coastal improvements were developed for discussions with stakeholders and project developers. Based on the analysis and

How uncertainty should be managed and communicated in policy-relevant scientific assessments is directly connected to the role of science and the responsibility of scientists. These fundamentally philosophical issues influence how scientific assessments are made and how scientific findings are communicated to policymakers. It is therefore of high importance to discuss implicit assumptions and value judgments that are made in policy-relevant scientific assessments. The present paper examines these issues for the case of scientific assessments of future sealevelrise. The magnitude of future sealevelrise is very uncertain, mainly due to poor scientific understanding of all physical mechanisms affecting the great ice sheets of Greenland and Antarctica, which together hold enough land-based ice to raise sealevels more than 60 meters if completely melted. There has been much confusion from policymakers on how different assessments of future sealevels should be interpreted. Much of this confusion is probably due to how uncertainties are characterized and communicated in these assessments. The present paper draws on the recent philosophical debate on the so-called "value-free ideal of science" - the view that science should not be based on social and ethical values. Issues related to how uncertainty is handled in scientific assessments are central to this debate. This literature has much focused on how uncertainty in data, parameters or models implies that choices have to be made, which can have social consequences. However, less emphasis has been on how uncertainty is characterized when communicating the findings of a study, which is the focus of the present paper. The paper argues that there is a tension between on the one hand the value-free ideal of science and on the other hand usefulness for practical applications in society. This means that even if the value-free ideal could be upheld in theory, by carefully constructing and hedging statements characterizing

The contribution to sea-levelrise from mountain glaciers and ice caps has grown over the past decades. They are expected to remain an important component of eustatic sea-levelrise for at least another century, despite indications of accelerated wastage of the ice sheets. However, it is difficult to project the future contribution of these small-scale glaciers to sea-levelrise on a global scale. Here, we project their volume changes due to melt in response to transient, spatially differentiated twenty-first century projections of temperature and precipitation from ten global climate models. We conduct the simulations directly on the more than 120,000 glaciers now available in the World Glacier Inventory, and upscale the changes to 19 regions that contain all mountain glaciers and ice caps in the world (excluding the Greenland and Antarctic ice sheets). According to our multi-model mean, sea-levelrise from glacier wastage by 2100 will amount to 0.124+/-0.037m, with the largest contribution from glaciers in Arctic Canada, Alaska and Antarctica. Total glacier volume will be reduced by 21+/-6%, but some regions are projected to lose up to 75% of their present ice volume. Ice losses on such a scale may have substantial impacts on regional hydrology and water availability.

High rates of wave-induced erosion along salt marsh boundaries challenge the idea that marsh survival is dictated by the competition between vertical sediment accretion and relative sea-levelrise. Because waves pounding marshes are often locally generated in enclosed basins, the depth and width of surrounding tidal flats have a pivoting control on marsh erosion. Here, we show the existence of a threshold width for tidal flats bordering salt marshes. Once this threshold is exceeded, irreversible marsh erosion takes place even in the absence of sea-levelrise. This catastrophic collapse occurs because of the positive feedbacks among tidal flat widening by wave-induced marsh erosion, tidal flat deepening driven by wave bed shear stress, and local wind wave generation. The threshold width is determined by analyzing the 50-y evolution of 54 marsh basins along the US Atlantic Coast. The presence of a critical basin width is predicted by a dynamic model that accounts for both horizontal marsh migration and vertical adjustment of marshes and tidal flats. Variability in sediment supply, rather than in relative sea-levelrise or wind regime, explains the different critical width, and hence erosion vulnerability, found at different sites. We conclude that sediment starvation of coastlines produced by river dredging and damming is a major anthropogenic driver of marsh loss at the study sites and generates effects at least comparable to the acceleratingsea-levelrise due to global warming.

An increase in the rate of sealevelrise is one of the primary impacts of projected global climate change. To assess potential inundation associated with a continued acceleration of sealevelrise, the highest resolution elevation data available were assembled from various sources and mosaicked to cover the land surfaces of the San Francisco Bay region. Next, to quantify high water levels throughout the bay, a hydrodynamic model of the San Francisco Estuary was driven by a projection of hourly water levels at the Presidio. This projection was based on a combination of climate model outputs and empirical models and incorporates astronomical, storm surge, El Niño, and long-term sealevelrise influences. Based on the resulting data, maps of areas vulnerable to inundation were produced, corresponding to specific amounts of sealevelrise and recurrence intervals. These maps portray areas where inundation will likely be an increasing concern. In the North Bay, wetland survival and developed fill areas are at risk. In Central and South bays, a key feature is the bay-ward periphery of developed areas that would be newly vulnerable to inundation. Nearly all municipalities adjacent to South Bay face this risk to some degree. For the Bay as a whole, as early as 2050 under this scenario, the one-year peak event nearly equals the 100-year peak event in 2000. Maps of vulnerable areas are presented and some implications discussed.

Caution is an essential ingredient in scientific investigations, as success in science depends on objective skepticism. In some cases a cultural resistance to scientific discovery has seemed to exist and there are other factors that can contribute to scientific reticence. In a case such as ice sheet instability and sealevelrise there is a danger that excessive caution might serve to lock in future disasters. I discussed these issues almost a decade ago (in Environ. Res. Lett., 2, 024002, 2007, doi:10.1088/1748-9326/2/2/024002), but given all that has transpired since then, this topic has become even more relevant and urgent. I will discuss the status of this dilemma as I see it.

Sealevel is rising in response to climate change. Currently the global mean rate is a little over 3 mm/year, but it is expected to accelerate significantly over this century. This will have a profound impact on coastal populations and infrastructure, including NASA centers and facilities. A detailed study proposed by the University of Colorado's Center for Astrodynamics Research on the impact of sealevelrise on a few of NASA's most vulnerable facilities was recently funded by NASA. Individual surveys at several high-risk NASA centers will be conducted and used as case studies for a broader investigation that needs to be done for coastal infrastructure around the country. The first year of the study will include implementing and conducting a terrestrial laser scanning (TLS) and GPS survey at Kennedy Space Center, Cape Canaveral, Florida, and potentially at Wallops Flight Facility, Wallops Island, Virginia, and Langley Research Center, Hampton, Virginia. We will use a broad array of geodetic tools to perform this study - much of which has been developed over the last few decades by NASA and its investigators. We will use airborne lidar data and terrestrial laser scanning (TLS) data to construct detailed digital elevation models (DEMs) of the facilities that we assess. We will use GPS data to assess the rate of vertical land movement at the facilities and to tie the DEM to tide gauges and other reference points. We will use satellite altimeter data from TOPEX, Jason-1, and Jason-2 to assess the sealevel changes observed near these NASA facilities over the last 20 years to see if it offers clues for the future. We will also use GRACE satellite gravity observations to predict the regional changes in sealevel caused by the melting of ice complexes around the world. We will use these datasets along with sealevel projections from global climate models (GCMs) and semi-empirical projections to make detailed maps of sealevel inundation for the years 2050 and 2100 for

Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-levelrise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sealevel (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1- 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the

Tropical cyclone (TC) intensification has been well documented in the science literature. TC intensification combined with sea-levelrise contributes to an enhanced risk to huge populations living near sealevel around the world. This study will apply spatial analysis techniques to combine the best available TC intensification data on storm surge, wave height and wind speeds; with digital elevation models and global population density estimates, to provide a first level evaluation of the increasing risk to human life and health.

The 3.2 +/- 0.2 millimeter per year global mean sealevelrise observed by the Topex/Poseidon satellite over 1993-98 is fully explained by thermal expansion of the oceans. For the period 1955-96, sealevelrise derived from tide gauge data agrees well with thermal expansion computed at the same locations. However, we find that subsampling the thermosteric sealevel at usual tide gauge positions leads to a thermosteric sealevelrise twice as large as the "true" global mean. As a possible consequence, the 20th century sealevelrise estimated from tide gauge records may have been overestimated.

This talk discusses the results of a NRC study on U.S. west coast sea-levelrise, completed in June. The first part of the study deals with global sealevelrise, utilizing data generated since the IPCC (2007) report and examining each of the major contributors to sea-level risel: thermal expansion of sea water in response to a warming atmosphere and ice melt from glaciers, ice caps, and ice sheets. Results show that land ice melt is currently the largest contributor to sealevelrise. Predictions of global sealevel are developed for 2030, 2050, and 2100. Next, regional sealevel is determined by including the effects of local vertical land motions, from tectonics, subsidence, and the spatial distribution of ice melt sealevel contributions (sealevel fingerprinting). Of particular interest is the potential of a Cascadia subduction zone earthquake that could add more than a meter of sea-levelrise in minutes in addition to the expected sealevelrise. Again, predictions of sea-levelrise for the shoreline of the west coast for 2030, 2050, and 2100 are determined. Implications of sealevelrise on storminess, and the erosion of beaches, coastal cliffs, and wetlands are discussed as well.

Global sealevel is rising and may accelerate with continued fossil fuel consumption from industrial and population growth. In 2012, the U.S. Geological Survey conducted more than 30 training and feedback sessions with Federal, State, and nongovernmental organization (NGO) coastal managers and planners across the northern Gulf of Mexico coast to evaluate user needs, potential benefits, current scientific understanding, and utilization of resource aids and modeling tools focused on sea-levelrise. In response to the findings from the sessions, this sea-levelrise modeling handbook has been designed as a guide to the science and simulation models for understanding the dynamics and impacts of sea-levelrise on coastal ecosystems. The review herein of decision-support tools and predictive models was compiled from the training sessions, from online research, and from publications. The purpose of this guide is to describe and categorize the suite of data, methods, and models and their design, structure, and application for hindcasting and forecasting the potential impacts of sea-levelrise in coastal ecosystems. The data and models cover a broad spectrum of disciplines involving different designs and scales of spatial and temporal complexity for predicting environmental change and ecosystem response. These data and models have not heretofore been synthesized, nor have appraisals been made of their utility or limitations. Some models are demonstration tools for non-experts, whereas others require more expert capacity to apply for any given park, refuge, or regional application. A simplified tabular context has been developed to list and contrast a host of decision-support tools and models from the ecological, geological, and hydrological perspectives. Criteria were established to distinguish the source, scale, and quality of information input and geographic datasets; physical and biological constraints and relations; datum characteristics of water and land components

The abrupt transition from fluvial to marine deposition of incised-valley-fill sediments retrieved from the southeast Vietnamese shelf, accurately records the postglacial transgression after 14 ka before present (BP). Valley-filling sediments consist of fluvial mud, whereas sedimentation after the transgression is characterized by shallow-marine carbonate sands. This change in sediment composition is accurately marked in high-resolution X-ray fluorescence (XRF) core scanning records. Rapid aggradation of fluvial sediments at the river mouth nearly completely filled the Mekong incised valley prior to flooding. However, accumulation rates strongly reduced in the valley after the river-mouth system flooded and stepped back. This also affected the sediment supply to deeper parts of the southeast Vietnamese shelf. Comparison of the Mekong valley-filling with the East Asian sea-level history of sub- and inter-tidal sediment records shows that the transgressive surface preserved in the incised-valley-fill records is a robust sea-level indicator. The valley was nearly completely filled with fluvial sediments between 13.0 and 9.5 ka BP when sea-level rose rather constantly with approximately 10 mm/yr, as indicated by the East Asian sea-level record. At shallower parts of the shelf, significant sediment reworking and the establishment of estuarine conditions at the final stage of infilling complicates accurate dating of the transgressive surface. Nevertheless, incised-valley-fill records and land-based drill sites indicate a vast and rapid flooding of the shelf from the location of the modern Vietnamese coastline to the Cambodian lowlands between 9.5 ka and 8.5 ka BP. Fast flooding of this part of the shelf is related with the low shelf gradient and a strong acceleration of the East Asian sea-levelrise from 34 to 9 meter below modern sealevel (mbsl) corresponding to the sea-level jump of melt water pulse (MWP) 1C.

Recent research has identified two fundamental unit processes that build delta distributary channels. The first is mouth-bar deposition at the shoreline and subsequent channel bifurcation, which is driven by progradation of the shoreline; the second is avulsion to a new channel, a result of aggradation of the delta topset. The former creates relatively small, branching networks such as Wax Lake Delta; the latter generates relatively few, long distributaries such as the Mississippi and Atchafalaya channels on the Mississippi Delta. The relative rate of progradation to aggradation, and hence the creation of accommodation space, emerges as a controlling parameter on channel network form. Field and experimental research has identified sealevel as the dominant control on Holocene delta growth worldwide, and has empirically linked channel network changes to changes in the rate of sealevelrise. Here I outline a simple modeling framework for distributary network evolution, and use this to explore large-scale changes in Holocene channel pattern that have been observed in deltas such as the Rhine-Meuse and Mississippi. Rapid early- to mid-Holocene sealevelrise forced many deltas into an aggradational mode, where I hypothesize that avulsion and the generation of large-scale branches should dominate. Slowing of sealevelrise in the last ˜6000 yr allowed partitioning of sediment into progradation, facilitating the growth of smaller-scale distributary trees at the shorelines of some deltas, and a reduction in the number of large-scale branches. Significant antecedent topography modulates delta response; the filling of large incised valleys, for example, caused many deltas to bypass the aggradational phase. Human effects on deltas can be cast in terms of geologic controls affecting accommodation: constriction of channels forces rapid local progradation and mouth-bar bifurcation, while acceleratedsealevelrise increases aggradation and induces more frequent channel

A series of dynamic penetration tests were performed up to a maximum depth of 2 m along sandy coastlines of Sardinia and Latium, Italy, in order to examine the change in resistance showed by sands. A maximum of resistance appears at the depth where the current sealevel varies with tide fluctuations; this maximum resistance is due to capillary forces, which occur and disappear two times a day. A second maximum of sand resistance was found about half a meter under the first. In two cases where it was possible to attribute an age to the sands showing this more ancient level, the ages were before 37 AD and about 1700 AD. The features of this compact sand level suggest that between these two ages the sealevel must have been practically constant, and unchanged until 300 years ago. These results were compared with tide gauge data recorded in the Netherlands, northern Italy and France. The data from the Amsterdam region, the oldest ones in the world, were reinterpreted as follows: the site of the Amsterdam tide gauge station is recognised as having undergone local settlements, while the entire region is denied to have been, as previously claimed, subject to a regional subsidence in the period of interest. As a consequence, also in the Amsterdam region the sealevel maintained nearly the same position at least from 1700 up to about 1800. Then this level, which as from now can be labelled as "pre-industrial", rose more and more rapidly, in agreement with the accelerated character of the increase of CO 2 in the atmosphere. In the Netherlands, northern Italy and France the amount of sealevelrise in the last 200 years seems to be slightly smaller (20-23 cm) than the mean sea rise in the world (about 27 cm), while in the study area (central Mediterranean) the sea rise is shown to be about twice as much. Another result of this study regards the tendency of sealevel change. The study showed that, of the two peaks of sand resistance found, the most recent peak is not

Digital media provide storytellers with dynamic new tools for communicating about scientific issues via interactive narrative visualizations. While traditional storytelling uses plot, characterization, and point of view to engage audiences with underlying themes and messages, interactive visualizations can be described as 'narrative builders' that promote insight through the process of discovery (Dove, G. & Jones, S. 2012, Proc. IHCI 2012). Narrative visualizations are used in online journalism to tell complex stories that allow readers to select aspects of datasets to explore and construct alternative interpretations of information (Segel, E. & Heer, J. 2010, IEEE Trans. Vis. Comp. Graph.16, 1139), thus enabling them to participate in the story-building process. Nevertheless, narrative visualizations also incorporate author-selected narrative elements that help guide and constrain the overall themes and messaging of the visualization (Hullman, J. & Diakopoulos, N. 2011, IEEE Trans. Vis. Comp. Graph. 17, 2231). One specific type of interactive narrative visualization that is used for science communication is the sealevelrise (SLR) viewer. SLR viewers generally consist of a base map, upon which projections of sealevelrise scenarios can be layered, and various controls for changing the viewpoint and scenario parameters. They are used to communicate the results of scientific modeling and help readers visualize the potential impacts of SLR on the coastal zone. Readers can use SLR viewers to construct personal narratives of the effects of SLR under different scenarios in locations that are important to them, thus extending the potential reach and impact of scientific research. With careful selection of narrative elements that guide reader interpretation, the communicative aspects of these visualizations may be made more effective. This presentation reports the results of a content analysis of a subset of existing SLR viewers selected in order to comprehensively

Global sea-levelrise is projected to accelerate two-to four-fold during the next century, increasing storm surge and shoreline retreat along low-lying, unconsolidated coastal margins. The Mississippi River Deltaic Plain in southeastern Louisiana is particularly vulnerable to erosion and inundation due to the rapid deterioration of coastal barriers combined with relatively high rates of land subsidence. Land-surface altitude data collected in the leveed areas of the New Orleans metropolitan region during five survey epochs between 1951 and 1995 indicated mean annual subsidence of 5 millimeters per year. Preliminary results of other studies detecting the regional movement of the north-central Gulf Coast indicate that the rate may be as much as 1 centimeter per year. Considering the rate of subsidence and the mid-range estimate of sea-levelrise during the next 100 years (480 millimeters), the areas of New Orleans and vicinity that are presently 1.5 to 3 meters below mean sealevel will likely be 2.5 to 4.0 meters or more below mean sealevel by 2100.

Glacial isostatic adjustment (GIA) encompasses a suite of geophysical phenomena accompanying the waxing and waning of continental-scale ice sheets. These involve the solid Earth, the oceans and the cryosphere both on short (decade to century) and on long (millennia) timescales. In the framework of contemporary sea-level change, the role of GIA is particular. In fact, among the processes significantly contributing to contemporary sea-level change, GIA is the only one for which deformational, gravitational and rotational effects are simultaneously operating, and for which the rheology of the solid Earth is essential. Here, I review the basic elements of the GIA theory, emphasizing the connections with current sea-level changes observed by tide gauges and altimetry. This purpose is met discussing the nature of the "sea-level equation" (SLE), which represents the basis for modeling the sea-level variations of glacial isostatic origin, also giving access to a full set of geodetic variations associated with GIA. Here, the SLE is employed to characterize the remarkable geographical variability of the GIA-induced sea-level variations, which are often expressed in terms of "fingerprints". Using harmonic analysis, the spatial variability of the GIA fingerprints is compared to that of other components of contemporary sea-level change. In closing, some attention is devoted to the importance of the "GIA corrections" in the context of modern sea-level observations, based on tide gauges or satellite altimeters.

Glacial isostatic adjustment (GIA) encompasses a suite of geophysical phenomena accompanying the waxing and waning of continental-scale ice sheets. These involve the solid Earth, the oceans and the cryosphere both on short (decade to century) and on long (millennia) timescales. In the framework of contemporary sea-level change, the role of GIA is particular. In fact, among the processes significantly contributing to contemporary sea-level change, GIA is the only one for which deformational, gravitational and rotational effects are simultaneously operating, and for which the rheology of the solid Earth is essential. Here, I review the basic elements of the GIA theory, emphasizing the connections with current sea-level changes observed by tide gauges and altimetry. This purpose is met discussing the nature of the "sea-level equation" (SLE), which represents the basis for modeling the sea-level variations of glacial isostatic origin, also giving access to a full set of geodetic variations associated with GIA. Here, the SLE is employed to characterize the remarkable geographical variability of the GIA-induced sea-level variations, which are often expressed in terms of "fingerprints". Using harmonic analysis, the spatial variability of the GIA fingerprints is compared to that of other components of contemporary sea-level change. In closing, some attention is devoted to the importance of the "GIA corrections" in the context of modern sea-level observations, based on tide gauges or satellite altimeters.

We estimate individual area and volume change by 2050 of all 83,460 glaciers of high mountain Asia (HMA), with a total area of 118,263 km2, delineated in the Randolph Glacier Inventory version 4.0 which separates glacier complexes in its previous version into individual glaciers. We used the 25 km resolution regional climate model RegCM 3.0 temperature and precipitation change projections forced by the IPCC A1B scenario. Glacier simulations were based on a novel surface mass balance-altitude parameterization fitted to observational data, and various volume-area scaling approaches using Shuttle Radar Topography Mission surface topography of each individual glacier. We generate mass balance-altitude relations for all the glaciers by region using nearest available glacier measurements. Two method are used to model the Equilibrium line altitude (ELA) variation. One is to use ELA sensitivities to temperature and precipitation change vary by region based on the relative importance of sublimation and melting processes. The other is solved ELA implicitly for every year using the temperature at ELA and Degree Day model. We project total glacier area loss in high mountain Asia in 2050 to be 22% of their extent in 2000, and they will contribute 5-8 mm to global sealevelrise.

Climate change impacts, such as acceleratedsea-levelrise, will affect stress gradients, yet impacts on competition/stress tolerance trade-offs and shifts in distributions are unclear. Ecosystems with strong stress gradients, such as estuaries, allow for space-for-time substitutions of stress factors and can give insight into future climate-related shifts in both resource and nonresource stresses. We tested the stress gradient hypothesis and examined the effect of increased inundation stress and biotic interactions on growth and survival of two congeneric wetland sedges, Schoenoplectus acutus and Schoenoplectus americanus. We simulated sea-levelrise across existing marsh elevations and those not currently found to reflect potential future sea-levelrise conditions in two tidal wetlands differing in salinity. Plants were grown individually and together at five tidal elevations, the lowest simulating an 80-cm increase in sealevel, and harvested to assess differences in biomass after one growing season. Inundation time, salinity, sulfides, and redox potential were measured concurrently. As predicted, increasing inundation reduced biomass of the species commonly found at higher marsh elevations, with little effect on the species found along channel margins. The presence of neighbors reduced total biomass of both species, particularly at the highest elevation; facilitation did not occur at any elevation. Contrary to predictions, we documented the competitive superiority of the stress tolerator under increased inundation, which was not predicted by the stress gradient hypothesis. Multifactor manipulation experiments addressing plant response to accelerated climate change are integral to creating a more realistic, valuable, and needed assessment of potential ecosystem response. Our results point to the important and unpredicted synergies between physical stressors, which are predicted to increase in intensity with climate change, and competitive forces on biomass as

Environmental heterogeneity is increasingly being used to select conservation areas that will provide for future biodiversity under a variety of climate scenarios. This approach, termed "conserving nature's stage" (CNS), assumes that environmental features will respond to climate change more slowly than biological communities, but is CNS effective when the stage is changing as rapidly as the climate? We tested the effectiveness of CNS to select conservation sites in salt marshes in coastal Georgia, USA, where environmental features will change rapidly due to sealevelrise (SLR). We calculated species diversity using distributions of a group of seven bird species with a wide variety of niches within Georgia salt marshes. Environmental heterogeneity was assessed across six landscape gradients (e.g., elevation, salinity, and patch area). We selected sites with high environmental heterogeneity using two approaches: a site complementarity approach ("Environmental Diversity" [ED]) and an approach that favors local environmental heterogeneity ("Environmental Richness" [ER]). We found that ER-selected sites could predict present-day species diversity better than randomly selected sites (up to an 8.1% improvement), while also being resilient to areal loss from SLR, and providing habitat to a particularly at-risk species. ED-selected sites did not perform well (no better or worse than random) in terms of predicting species diversity and will not be resilient to SLR. Despite the discrepancy between the two approaches, CNS is a viable strategy for conservation site selection in salt marshes, and potentially other coastal areas where SLR will affect environmental features, but performance may depend on the magnitude of geological changes caused by SLR. Our results indicate that conservation planners using CNS that had heretofore ignored low-lying coasts (due to concerns of SLR) could include coastal ecosystems in regional planning strategies. This article is protected by

Coastal populations and wetlands have been intertwined for centuries, whereby humans both influence and depend on the extensive ecosystem services that wetlands provide. Although coastal wetlands have long been considered vulnerable to sea-levelrise, recent work has identified fascinating feedbacks between plant growth and geomorphology that allow wetlands to actively resist the deleterious effects of sea-levelrise. Humans alter the strength of these feedbacks by changing the climate, nutrient inputs, sediment delivery and subsidence rates. Whether wetlands continue to survive sea-levelrise depends largely on how human impacts interact with rapid sea-levelrise, and socio-economic factors that influence transgression into adjacent uplands.

We describe an analysis framework to determine military installation vulnerabilities under increases in local mean sealevel as projected over the next century. The effort is in response to an increasing recognition of potential climate change ramifications for national security and recommendations that DoD conduct assessments of the impact on U.S. military installations of climate change. Results of the effort described here focus on development of a conceptual framework for sealevelrise vulnerability assessment at coastal military installations in the southwest U.S. We introduce the vulnerability assessment in the context of a risk assessment paradigm that incorporates sources in the form of future sealevel conditions, pathways of impact including inundation, flooding, erosion and intrusion, and a range of military installation specific receptors such as critical infrastructure and training areas. A unique aspect of the methodology is the capability to develop wave climate projections from GCM outputs and transform these to future wave conditions at specific coastal sites. Future sealevel scenarios are considered in the context of installation sensitivity curves which reveal response thresholds specific to each installation, pathway and receptor. In the end, our goal is to provide a military-relevant framework for assessment of accelerated SLR vulnerability, and develop the best scientifically-based scenarios of waves, tides and storms and their implications for DoD installations in the southwestern U.S. ?? 2011 MTS.

In view of the scientific and social implications, the global mean sealevelrise (GMSLR) and its possible causes and future trend have been a challenge for so long. For the twentieth century, reconstructions generally indicate a rate of GMSLR in the range of 1.5 to 2.0 mm yr-1. However, the existence of nonlinear trends is still debated, and current estimates of the secular acceleration are subject to ample uncertainties. Here we use various GMSLR estimates published on scholarly journals since the 1940s for a heuristic assessment of global sealevelacceleration. The approach, alternative to sealevel reconstructions, is based on simple statistical methods and exploits the principles of meta-analysis. Our results point to a global sealevelacceleration of 0.54 ± 0.27 mm/yr/century (1σ) between 1898 and 1975. This supports independent estimates and suggests that a sealevelacceleration since the early 1900s is more likely than currently believed.

Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sealevel over the past 8.5 million years. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~ 20 m/Myr) and our numerical modeling results suggest that low sealevels (50–125 m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sealevel was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.

Mountain glaciers and ice caps (MG&IC) have been identified as primary source of eustatic sealevelrise, ahead of the ice sheets, during recent decades. The Intergovernmental Panel on Climate Change (IPCC) estimates that the sum of all contributions to sea-levelrise for the period 1961-2004 was 1.1± 0.5 mm a-1, leaving 0.7±0.7 of the 1.8±0.5 mm a-1 observed sea-levelrise unexplained. Here, we compute the global surface mass balance of all mountain glaciers and ice caps and find that part of this much-discussed gap can be attributed to a larger contribution than previously assumed from mass loss of MG&IC, especially those around the Antarctic Peninsula. We find a global surface mass loss of all MG&IC of 0.79±0.34 mm a-1 sea-level equivalent compared to IPCC’s 0.50±0.18 mm a-1. The Antarctic MG&IC contributed 28% of the global estimate due to exceptional warming around the Antarctic Peninsula and high mass-balance sensitivities to temperature similar to those we find in maritime Iceland, Patagonia and Alaska. Our results highlight the role of the MG&IC around the Antarctic Peninsula where climate is distinctly different from the cold conditions of the ice sheet, and large mass balance sensitivities to temperature, exceptional warming and large area combine to yield large potential for glacier mass loss. We emphasize an urgent need for improved glacier inventory and in-situ mass balance data from this region especially in light of recently accelerated mass loss from MG&IC.

Tidal marshes have a large capacity for producing and storing organic matter, making their role in the global carbon budget disproportionate to land area. Most of the organic matter stored in these systems is in soils where it contributes 2-5 times more to surface accretion than an equal mass of minerals. Soil organic matter (SOM) sequestration is the primary process by which tidal marshes become perched high in the tidal frame, decreasing their vulnerability to accelerated relative sealevelrise (RSLR). Plant growth responses to RSLR are well understood and represented in century-scale forecast models of soil surface elevation change. We understand far less about the response of SOM decomposition to accelerated RSLR. Here we quantified the effects of flooding depth and duration on SOM decomposition by exposing planted and unplanted field-based mesocosms to experimentally manipulated relative sealevel over two consecutive growing seasons. SOM decomposition was quantified as CO2 efflux, with plant- and SOM-derived CO2 separated via δ(13) CO2 . Despite the dominant paradigm that decomposition rates are inversely related to flooding, SOM decomposition in the absence of plants was not sensitive to flooding depth and duration. The presence of plants had a dramatic effect on SOM decomposition, increasing SOM-derived CO2 flux by up to 267% and 125% (in 2012 and 2013, respectively) compared to unplanted controls in the two growing seasons. Furthermore, plant stimulation of SOM decomposition was strongly and positively related to plant biomass and in particular aboveground biomass. We conclude that SOM decomposition rates are not directly driven by relative sealevel and its effect on oxygen diffusion through soil, but indirectly by plant responses to relative sealevel. If this result applies more generally to tidal wetlands, it has important implications for models of SOM accumulation and surface elevation change in response to accelerated RSLR.

The major cause of the Hawaiian Islands coastal erosion is shown to be not global warming, but the sinking of the volcanic islands. The geologic "circle-of-life" beyond the Hawaiian hot spot is the true explanation of the beach erosion. The sealevels are slow rising and not accelerating worldwide as well as in the United States. In the specific of the Hawaii Islands, they have been decelerating over the last 3 decades because of the phasing of the multi-decadal oscillations for this area of the Pacific. There is therefore no evidence coastal erosion will double in the Hawaii by 2050 because of global warming.

There is a broader awareness than ever that we live in a changing environment. The spectre of climate change is of wide concern, and the observed trends and anticipated consequences of an acceleration of sea-levelrise pose a series of threats for the future of people who live in coastal communities. Coastal geoscientists are able to reconstruct the position of former sealevels; they can also explain much of the geographical variation in relative sea-level history. Successive collaborative projects (many under the auspices of international programmes sponsored by IGCP and INQUA) derived local sea-level histories and compiled atlases of relative sea-level curves, and some addressed past coastal behaviour in response to these changes. The most recent International Geological Correlation programme project 588, 'Preparing for coastal change', continues this impressive lineage of projects that have laid the foundations for our understanding of sea-level behaviour over the late Quaternary. Today, these issues are a major focus in the debate about climate change, its impacts, and the need for adaptation on the most vulnerable shorelines. There is clearly a role for the palaeoenvironmental skillset honed through successive geoscientific projects. Investigations of past coastal environments have provided the tools for delineating past levels of the sea, but the stratigraphical and geochronological studies which were necessary to reconstruct the sea-level position also provide insights into where the shoreline lay and how the coast behaved as sealevel changed. If the present is the key to the past, then the past, seen from the context of the present, can be a guide to the future. Collaborative projects and international co-operation between scientists from different disciplines can play important roles in future debates about how our world will change. First, the lessons learnt about the patterns of variation of relative sealevel need to be more widely recognised by

The detection of acceleration in mean sealevel around the data-rich margins of the United States has been a keen endeavour of sea-level researchers following the seminal work of Bruce Douglas in 1992. Over the past decade, such investigations have taken on greater prominence given mean sealevel remains a key proxy by which to measure a changing climate system. The physics-based climate projection models are forecasting that the current global average rate of mean sea-levelrise (≈3 mm/y) might climb to rates in the range of 10020 mm/y by 2100. Most research in this area has centred on reconciling current rates of rise with the significant accelerations required to meet the forecast projections of climate models. The analysis in this paper is based on a recently developed analytical package titled "msltrend," specifically designed to enhance estimates of trend, real-time velocity and acceleration in the relative mean sea-level signal derived from long annual average ocean-water-level time series. Key findings are that at the 95% confidence level, no consistent or substantial evidence (yet) exists that recent rates of rise are higher or abnormal in the context of the historical records available for the United States, nor does any evidence exist that geocentric rates of rise are above the global average. It is likely that a further 20 years of data will identify whether recent increases east of Galveston and along the east coast are evidence of the onset of climate change induced acceleration.

Sealevel has been steadily rising over the past century, predominantly due to anthropogenic climate change. The rate of sealevelrise will keep increasing with continued global warming, and, even if temperatures are stabilized through the phasing out of greenhouse gas emissions, sealevel is still expected to rise for centuries. This will affect coastal areas worldwide, and robust projections are needed to assess mitigation options and guide adaptation measures. Here we combine the equilibrium response of the main sealevelrise contributions with their last century's observed contribution to constrain projections of future sealevelrise. Our model is calibrated to a set of observations for each contribution, and the observational and climate uncertainties are combined to produce uncertainty ranges for 21st century sealevelrise. We project anthropogenic sealevelrise of 28–56 cm, 37–77 cm, and 57–131 cm in 2100 for the greenhouse gas concentration scenarios RCP26, RCP45, and RCP85, respectively. Our uncertainty ranges for total sealevelrise overlap with the process-based estimates of the Intergovernmental Panel on Climate Change. The “constrained extrapolation” approach generalizes earlier global semiempirical models and may therefore lead to a better understanding of the discrepancies with process-based projections. PMID:26903648

Estuaries are transitional ecosystems located at the margin of the land and ocean and as a result they are particularly sensitive to sealevelrise and other climate drivers. In this presentation, we summarize the potential impacts of sealevelrise on key estuarine habitats inc...

Estuaries are transitional ecosystems located at the margin of the land and ocean and as a result they are particularly sensitive to sealevelrise and other climate drivers. In this presentation, we summarize the potential impacts of sealevelrise on key estuarine habitats incl...

Sealevel has been steadily rising over the past century, predominantly due to anthropogenic climate change. The rate of sealevelrise will keep increasing with continued global warming, and, even if temperatures are stabilized through the phasing out of greenhouse gas emissions, sealevel is still expected to rise for centuries. This will affect coastal areas worldwide, and robust projections are needed to assess mitigation options and guide adaptation measures. Here we combine the equilibrium response of the main sealevelrise contributions with their last century's observed contribution to constrain projections of future sealevelrise. Our model is calibrated to a set of observations for each contribution, and the observational and climate uncertainties are combined to produce uncertainty ranges for 21st century sealevelrise. We project anthropogenic sealevelrise of 28-56 cm, 37-77 cm, and 57-131 cm in 2100 for the greenhouse gas concentration scenarios RCP26, RCP45, and RCP85, respectively. Our uncertainty ranges for total sealevelrise overlap with the process-based estimates of the Intergovernmental Panel on Climate Change. The "constrained extrapolation" approach generalizes earlier global semiempirical models and may therefore lead to a better understanding of the discrepancies with process-based projections.

The Liaohe Delta in China is an ecologically and commercially important wetland system under threat from sealevelrise and marsh subsidence. Sediments deposited in coastal marshes could offer wetlands a potentially important means for adjusting surface elevation with risingsealevel, yet coastal wetland stability in Liaohe Delta is not well understood due to limited data from long-term experiments. In this study, wetland surface elevation and vertical accretion were measured from 2011 to 2015 using a surface elevation table (SET) and feldspar marker horizons in two Phragmites and two Suaeda marshes receiving Liaohe River water. The analysis shows that the Phragmites marshes exhibited higher rates of marsh accretion and elevation change than the Suaeda marshes. The two Phragmites marsh sites had average surface elevation change rates at 8.8 and 9.3 mm yr-1, vertical accretion at 17.4 and 17.6 mm yr-1, and shallow subsidence at 8.6 and 8.3 mm yr-1. The average rates of elevation change, vertical accretion, and shallow subsidence at two Suaeda marsh sites were 5.8 and 6.3 mm yr-1, 13.6 and 14.8 mm yr-1, and 7.8 and 8.5 mm yr-1, respectively. The trends suggest that coastal marshes in Liaohe Delta are experiencing changes in average soil elevation that range from a net increase of 0.3 mm y-1 to 6.9 mm y-1 relative to averaged sealevelrise in Bohai Sea reported by the 2016 State Oceanic Administration People's Republic of China projection (2.4-5.5 mm y-1), which indicated that the four wetland sites would adjust to the sealevelrise and even continue to gain elevation, especially for the Phragmites sites. Nevertheless, the vulnerability of coastal wetlands in Liaohe Delta need further assessment considering the acceleratedsealevelrise, the high rate of subsidence, and the declining sediment delivery owing to anthropogenic activities such as dam constructions in the river basin.

Since the turn of the twentieth century, industrial-scale redistribution of water from landlocked aquifers to the ocean has driven up the global average sealevel by more than 12 centimeters. Between 1900 and 2008, roughly 4500 cubic kilometers of water was drawn from the ground, largely to feed an agricultural system increasingly reliant on irrigation. Of that 4500-cubic-kilometer total (nearly the volume of Lake Michigan), 1100 cubic kilometers were pumped out between 2000 and 2008 alone. This early-21st-century groundwater depletion was responsible for raising global sealevel at a rate of 0.4 millimeter per year, an eighth of the observed total. These updated values, falling near the middle of the range of previous estimates, are the product of an investigation by Konikow that drew together a variety of volumetric measurements of groundwater storage.

The present-day calving flux from Greenland and Antarctica is poorly known, and this accounts for a significant portion of the uncertainty in the current mass balance of these ice sheets. Similarly, the lack of knowledge about the role of calving in glacier dynamics constitutes a major uncertainty in predicting the response of glaciers and ice sheets to changes in climate and thus sealevel. Another fundamental problem has to do with incomplete knowledge of glacier areas and volumes, needed for analyses of sea-level change due to changing climate. The authors proposed to develop an improved ability to predict the future contributions of glaciers to sealevel by combining work from four research areas: remote sensing observations of calving activity and iceberg flux, numerical modeling of glacier dynamics, theoretical analysis of the calving process, and numerical techniques for modeling flow with large deformations and fracture. These four areas have never been combined into a single research effort on this subject; in particular, calving dynamics have never before been included explicitly in a model of glacier dynamics. A crucial issue that they proposed to address was the general question of how calving dynamics and glacier flow dynamics interact.

Sea-levelrise is a major effect of climate change. It has drawn international attention, because higher sealevels in the future would cause serious impacts in various parts of the world. There are questions associated with sea-levelrise which science needs to answer. To what extent did climate change contribute to sea-levelrise in the past? How much will global mean sealevel increase in the future? How serious are the impacts of the anticipated sea-levelrise likely to be, and can human society respond to them? This paper aims to answer these questions through a comprehensive review of the relevant literature. First, the present status of observed sea-levelrise, analyses of its causes, and future projections are summarized. Then the impacts are examined along with other consequences of climate change, from both global and Japanese perspectives. Finally, responses to adverse impacts will be discussed in order to clarify the implications of the sea-levelrise issue for human society. PMID:23883609

Sea-levelrise is a major effect of climate change. It has drawn international attention, because higher sealevels in the future would cause serious impacts in various parts of the world. There are questions associated with sea-levelrise which science needs to answer. To what extent did climate change contribute to sea-levelrise in the past? How much will global mean sealevel increase in the future? How serious are the impacts of the anticipated sea-levelrise likely to be, and can human society respond to them? This paper aims to answer these questions through a comprehensive review of the relevant literature. First, the present status of observed sea-levelrise, analyses of its causes, and future projections are summarized. Then the impacts are examined along with other consequences of climate change, from both global and Japanese perspectives. Finally, responses to adverse impacts will be discussed in order to clarify the implications of the sea-levelrise issue for human society.(Communicated by Kiyoshi HORIKAWA, M.J.A.).

Strong evidence on climate change underscores the need for actions to reduce the impacts of sea-levelrise. It has been largely unrecognized that low-lying coastal areas are more vulnerable to inundation from groundwater than marine flooding because the groundwater elevation is typically higher than mean sealevel. Field measurements of the coastal groundwater elevation and tidal influence in urban Honolulu, Hawaii, allow estimates of the generalized distribution of the mean water table, which was used in conjunction with digital elevation maps to assess vulnerability to groundwater inundation from sea-levelrise. We find that 0.6 m of potential sea-levelrise causes substantial flooding, and 1 m sea-levelrise inundates 10% of a 1-km wide coastal zone. This has wide-reaching consequences for decision-makers, resource managers, and urban planners and is applicable to many low-lying coastal areas.

Carbon uptake and storage in marine and terrestrial systems is a topic of considerable importance, given the current rate of increase in atmospheric carbon dioxide concentrations. This project investigates how sealevelrise and nutrient enrichment impact salt marsh accretion in the Waquoit Bay Estuary on the southwest coast of Cape Cod, MA, USA. The region is a recognized hot spot of sealevelrise over the past 25 years, and it has experienced accelerated nitrogen enrichment related to population growth over the past 60 years. Eleven piston cores were collected from four marshes experiencing a gradient in nutrient enrichment. Preliminary results are based on a 90 cm core from Sage Lot Pond that spans approximately 490 years. Sediment accretion rates, determined from 137Cs and 210Pb, indicate an acceleration in marsh vertical growth since 1950. Concurrent evaluation of bulk carbon content shows increased carbon burial over the same time period. Additionally, sediment nitrogen content has increased while δ15N values became heavier, potentially indicative of anthropogenic nitrogen loading. These data will contribute to our understanding of the capacity of the marshes to contribute to carbon burial while responding to changes in climate and land use.

Sealevels are expected to rise as a result of global temperature increases, one implication of which is the potential exacerbation of sea water intrusion into coastal aquifers. Given that approximately 70% of the world's population resides in coastal regions, it is imperative to understand the interaction between fresh groundwater and sea water intrusion in order to best manage available resources. For this study, controlled investigation has been carried out concerning the temporal variation in sea water intrusion as a result of risingsealevels. A series of fixed inland head two-dimensional sea water intrusion models were developed with SEAWAT in order to assess the impact of risingsealevels on the transient migration of saline intrusion in coastal aquifers under a range of hydrogeological property conditions. A wide range of responses were observed for typical hydrogeological parameter values. Systems with a high ratio of hydraulic conductivity to recharge and high effective porosity lagged behind the equilibrium sea water toe positions during sea-levelrise, often by many hundreds of meters, and frequently taking several centuries to equilibrate following a cease in sea-levelrise. Systems with a low ratio of hydraulic conductivity to recharge and low effective porosity did not develop such a large degree of disequilibrium and generally stabilized within decades following a cease in sea-levelrise. This study provides qualitative initial estimates for the expected rate of intrusion and predicted degree of disequilibrium generated by sea-levelrise for a range of hydrogeological parameter values.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Gulf Islands National Seashore (GUIS) in Mississippi and Florida. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The Gulf Islands in Mississippi and Florida consist of stable and washover dominated portions of barrier beach backed by wetland and marsh. The areas likely to be most vulnerable to sea-levelrise are those with the highest occurrence of overwash, the highest rates of shoreline change, the gentlest regional coastal slope, and the highest rates of relative sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers.

According to coastal measurements, global mean sea-level has risen at a rate of 1.8 mm yr -1 between 1950 and 2000, with large spatial variability at regional scales. Within the Bay of Biscay, trends computed from coastal tide gauges records have revealed that sea-levelrise is accelerating over this period of time; this is in agreement with rates obtained from satellite imagery in the open ocean since 1993. The objectives of the present study are: (1) to assess the evidence of the relative sea-levelrise on coastal morphology and habitats in the Gipuzkoan littoral zone (Basque coast, northern Spain) for the period 1954-2004, and (2) to evaluate the relative contribution of local anthropogenic versus sea-levelrise impacts for explaining inter-supratidal habitat changes. A high-resolution airborne laser altimetry data (LIDAR) has been used to derive a Digital Terrain Model (DTM) of 15-cm vertical resolution. Coastal habitats were mapped for two periods, using historic airborne photography (1954) and high-resolution imagery (2004). Analysis of tide gauge records from Santander (northern Spain) has revealed that relative mean sea-level has been rising at a rate of 2.08 ± 0.33 mm yr -1 from 1943 to 2004; this is consistent with sea-level trends from other measurements within the area (St. Jean de Luz and Bilbao), obtained over shorter periods of time, and with previous results obtained in the Bay of Biscay. Based upon this sea-level trend and by means of a LIDAR-based DTM, the results have indicated that the predicted change along the Gipuzkoan coast due to sea-levelrise was of 11.1 ha within the 50-yr period. In contrast, comparison of historical and recent orthophotography has detected only 2.95 ha of change, originated possibly from sea-levelrise, and 98 ha transformed by anthropogenic impacts. Hence, coastal changes due to sea-levelrise might be overwhelmed by excessive human impacts, at the spatial and temporal scales of the analysis. This work highlights

In Bangladesh, the Ganges, Brahmaputra, and Meghna Rivers come together to form the largest river delta in the world. This low-lying region of the Bay of Bengal is one of the most densely populated in the world and is prone to monsoonal flooding, potentially aggravated by intensified cyclones due to climate change. In this context, sea-levelrise, along with tectonic, sediment load and groundwater extraction induced land uplift/subsidence, significantly exacerbate the Bangladesh's coastal vulnerability. Here we present the goals and results of a Belmont Forum/IGFA-funded project, BanD-AID (http://Belmont-SeaLevel.org). For the last 5 decades, we analyze the decadal / multi-decadal sealevel in this region. To do this, we use a reconstruction of sealevel past variations over the past 50 years based on the joint statistical analysis of tide gauge records and grids of sealevel from a ocean circulation model. We also determine the relative sealevel trend, which reflects the sealevel change felt by the population locally, by combining space geodetic observations, including satellite altimetry and GPS, together with tide gauges, and different reconstructed sea-level approaches. This unique combination of different techniques offers the possibility to better quantify the major contributions to the relative sea-levelrise at the Bangladesh delta, towards addressing its coastal vulnerability and future sustainability.

The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-levelrise, relatively little is known about how decomposition rates will respond to sea-levelrise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-levelrise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive acceleratingsea-levelrise.

Submarine mass failures (which include submarine slides or submarine landslides) occur widely on open continental margins. Understanding their cause is of great importance in view of the danger that they can pose both to coastal populations through tsunamis and to the exploitation of ocean floor resources through mass movement of the sea floor. Present knowledge of the causes of submarine mass failures is briefly reviewed, focussing on the role of sealevelrise, a process which has previously only infrequently been cited as a cause. It is argued that sealevelrise could easily have been involved in at least some of these events by contributing to increased overpressure in sediments of the continental margin whilst causing seismic activity. The Holocene Storegga Slide off South West Norway may have been partly caused by the early Holocene sealevelrise in the area, accentuated by meltwater flux from the discharges of Lake Agassiz-Ojibway in North America. Relative sealevelrise increased water loading on the Norwegian continental margin, increasing overpressure in the sediments and also causing seismic activity, triggering the Holocene Storegga Slide. Given that some forecasts of future sealevelrise are not greatly different from rises which obtained during the early Holocene, the implications of risingsealevels for submarine mass failures in a global warming world are considered.

A research study to examine the ability to predict changes in coastal vegetation caused by sealevelrise is very briefly summarized. A field survey was carried out on the northwest coast of Florida. A predictive elevation model was then generated from digitized US Geologic Survey 1:2400 hypsographic data using surface modeling techniques. Sea-levelrise model simulations were generated to predict a likelihood index of habitat change and conversions under different scenarios. Maps were produced depicting location of the coastline and inland extent of salt marsh using a range of sealevelrise rates through the year 2100. This modeling approach offers a technological tool to researchers and wetland managers for effective cumulative impact analysis of wetlands affected by sea-levelrise.

Globally, seabirds are vulnerable to anthropogenic threats both at sea and on land. Seabirds typically nest colonially and show strong fidelity to natal colonies, and such colonies on low-lying islands may be threatened by sea-levelrise. We used French Frigate Shoals, the largest atoll in the Hawaiian Archipelago, as a case study to explore the population dynamics of seabird colonies and the potential effects sea-levelrise may have on these rookeries. We compiled historic observations, a 30-year time series of seabird population abundance, lidar-derived elevations, and aerial imagery of all the islands of French Frigate Shoals. To estimate the population dynamics of 8 species of breeding seabirds on Tern Island from 1980 to 2009, we used a Gompertz model with a Bayesian approach to infer population growth rates, density dependence, process variation, and observation error. All species increased in abundance, in a pattern that provided evidence of density dependence. Great Frigatebirds (Fregata minor), Masked Boobies (Sula dactylatra), Red-tailed Tropicbirds (Phaethon rubricauda), Spectacled Terns (Onychoprion lunatus), and White Terns (Gygis alba) are likely at carrying capacity. Density dependence may exacerbate the effects of sea-levelrise on seabirds because populations near carrying capacity on an island will be more negatively affected than populations with room for growth. We projected 12% of French Frigate Shoals will be inundated if sealevelrises 1 m and 28% if sealevelrises 2 m. Spectacled Terns and shrub-nesting species are especially vulnerable to sea-levelrise, but seawalls and habitat restoration may mitigate the effects of sea-levelrise. Losses of seabird nesting habitat may be substantial in the Hawaiian Islands by 2100 if sealevelsrise 2 m. Restoration of higher-elevation seabird colonies represent a more enduring conservation solution for Pacific seabirds.

Explore how melting ice sheets affect global sealevels. Sea-levelrise (SLR) is a rise in the water level of the Earth's oceans. There are two major kinds of ice in the polar regions: sea ice and land ice. Land ice contributes to SLR and sea ice does not. This article explores the characteristics of sea ice and land ice and provides some hands-on…

Globally, seabirds are vulnerable to anthropogenic threats both at sea and on land. Seabirds typically nest colonially and show strong fidelity to natal colonies, and such colonies on low-lying islands may be threatened by sea-levelrise. We used French Frigate Shoals, the largest atoll in the Hawaiian Archipelago, as a case study to explore the population dynamics of seabird colonies and the potential effects sea-levelrise may have on these rookeries. We compiled historic observations, a 30-year time series of seabird population abundance, lidar-derived elevations, and aerial imagery of all the islands of French Frigate Shoals. To estimate the population dynamics of 8 species of breeding seabirds on Tern Island from 1980 to 2009, we used a Gompertz model with a Bayesian approach to infer population growth rates, density dependence, process variation, and observation error. All species increased in abundance, in a pattern that provided evidence of density dependence. Great Frigatebirds (Fregata minor), Masked Boobies (Sula dactylatra), Red-tailed Tropicbirds (Phaethon rubricauda), Spectacled Terns (Onychoprion lunatus), and White Terns (Gygis alba) are likely at carrying capacity. Density dependence may exacerbate the effects of sea-levelrise on seabirds because populations near carrying capacity on an island will be more negatively affected than populations with room for growth. We projected 12% of French Frigate Shoals will be inundated if sealevelrises 1 m and 28% if sealevelrises 2 m. Spectacled Terns and shrub-nesting species are especially vulnerable to sea-levelrise, but seawalls and habitat restoration may mitigate the effects of sea-levelrise. Losses of seabird nesting habitat may be substantial in the Hawaiian Islands by 2100 if sealevelsrise 2 m. Restoration of higher-elevation seabird colonies represent a more enduring conservation solution for Pacific seabirds.

Different characteristics of Spartina maritima found in two distinct salt marshes located in different estuaries were analysed through interpretation of their local hydrodynamic patterns, as well as the impact of sealevelrise on physical processes and consequently on plant dynamics and salt marshes stability. These salt marshes are situated in two of the most important Portuguese coastal systems, Tagus estuary (Rosário salt marsh) and Ria de Aveiro lagoon (Barra salt marsh), which are dominated by physical processes that induce strong tidal currents. They were monitored during one year and plant and sediment samples of S. maritima were collected quarterly in order to determine the vegetation coverage, above and belowground biomass, organic matter and sediment moisture. Residual circulation, tidal asymmetry and tidal dissipation were determined from numerical modelling results of the MOHID 2D model that was applied to each coastal system, considering the actual sealevel and a sealevelrise (SLR) scenario. Results suggest that the different characteristics found for Spartina maritima in the Rosário and the Barra salt marshes may be related with the diverse hydrodynamic conditions identified for each salt marsh. Consequently, the exploration of SLR scenario predictions indicates how these salt marshes could evolve in the future, showing that the important changes in these hydrodynamic parameters under climate change context might induce significant modifications in the salt marshes dynamics and stability. SLR scenario could lead to changes in nutrients and sediments patterns around the salt marshes and thus vegetation coverage percentage would be affected. Additionally, as a consequence of flood duration increase, sediment moisture will increase causing a stress condition to plants. Hence, the ratio below/aboveground biomass might increase, becoming critical to plants survival under conditions of acceleratedsealevelrise. Accordingly, both SLR and expected

Observations from the global array of tide gauges show that global sea-level has been rising at an average rate of 1.5-2 mm/yr during the last ˜ 150 years (Spada & Galassi, 2012). Although a global sea-levelacceleration was initially ruled out, subsequent studies have coherently proposed values of ˜1 mm/year/century (Olivieri & Spada, 2012). More complex non-linear trends and abrupt sea-level variations have now also been recognized. Globally, they could manifest a regime shift between the late Holocene and the current rhythms of sea-levelrise, while locally they result from ocean circulation anomalies, steric effects and wind stress (Bromirski et al. 2011). Although isostatic readjustment affects the local rates of secular sea-level change, a possible impact on regional acceleration have been so far discounted (Woodworth et al., 2009) since the process evolves on a millennium scale. Here we report a previously unnoticed anomaly in the long-term sea-levelacceleration of the Baltic Sea tide gauge records, and we explain it by the classical post-glacial rebound theory and numerical modeling of glacial isostasy. Contrary to previous assumptions, our findings demonstrate that isostatic compensation plays a role in the regional secular sea-levelacceleration. In response to glacial isostatic adjustment (GIA), tide gauge records located along the coasts of the Baltic Sea exhibit a small - but significant - long-term sea-levelacceleration in excess to those in the far field of previously glaciated regions. The sign and the amplitude of the anomaly is consistent with the post-glacial rebound theory and with realistic numerical predictions of GIA models routinely employed to decontaminate the tide gauges observations from the GIA effects (Peltier, 2004). Model computations predict the existence of anomalies of similar amplitude in other regions of the globe where GIA is still particularly vigorous at present, but no long-term instrumental observations are available to

Sea-levelrise from melting of polar ice sheets is one of the largest potential threats of future climate change. Polar warming by the year 2100 may reach levels similar to those of 130,000 to 127,000 years ago that were associated with sealevels several meters above modern levels; both the Greenland Ice Sheet and portions of the Antarctic Ice Sheet may be vulnerable. The record of past ice-sheet melting indicates that the rate of future melting and related sea-levelrise could be faster than widely thought.

In this study, an integrated model to assess the effect of sealevelrise on salt marsh systems is presented. It is based on a coupled two-dimensional hydrodynamic model and a parametric marsh model. The model shows marsh productivity as a function of mean high water (MHW), mean low water (MLW), and the elevation of the marsh platform. MHW and MLW are the mean high and low water levels over a tidal record and the marsh platform elevation is the elevation of the thick and smooth piled up sediments and biomass that support the productivity of the marsh. MHW and MLW throughout a river and tidal creeks are determined by time varying tides resulting from the two-dimensional hydrodynamic model. In order to calculate accurate biomass productivity, and MHW and MLW elevations, a digital elevation model (DEM) representing the marsh table elevation and tidal creeks with high accuracy is necessary (Hagen et al., 2013). There are optimum ranges for relative sealevelrise (RSLR), mean sealevel (MSL), and depth of inundation for salt marshes to increase productivity. Because of the constantly changing MSL, the marsh always adjusts itself to a new equilibrium (Morris, et al., 2002). In the marsh model, the sediment accretion rate, which is a function of the marsh productivity, is considered. The tidal record is calculated by the hydrodynamic model and the DEM is adjusted by incorporating the accretion rate over a period of time, provided by the marsh model. Then, the new tidal record is assessed by running the hydrodynamic model, considering sealevelrise with the new marsh table elevations. Using the new tidal record, the marsh productivity is simulated. This process can be divided into short time steps to capture changes in the rate of sealevelrise. For example, a 68 cm sealevelrise over 63 years can be split into five- or ten- year periods to have a linear trend for sealevelrise in each period. The model is examined for the lower St. Johns River and Apalachicola River

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Point Reyes National Seashore in Northern California. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Point Reyes National Seashore consists of sand and gravel beaches, rock cliffs, sand dune cliffs, and pocket beaches. The areas within Point Reyes that are likely to be most vulnerable to sea-levelrise are areas of unconsolidated sediment where the coastal slope is lowest and wave energy is high.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Cape Hatteras National Seashore (CAHA) in North Carolina. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, historical shoreline change rates, mean tidal range, and mean significant wave height. The rankings for each variable were combined and an index value was calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Cape Hatteras National Seashore consists of stable and washover dominated segments of barrier beach backed by wetland and marsh. The areas within Cape Hatteras that are likely to be most vulnerable to sea-levelrise are those with the highest occurrence of overwash and the highest rates of shoreline change.

The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to risingsealevels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-levelrise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-levelrise. We identified fundamental differences in how resilience is maintained across wetland community types, which have important implications for management activities that aim to restore or conserve resilient systems. We showed that the relative importance of surface and subsurface processes in controlling wetland surface elevation change differed between TFFWs and oligohaline marshes. The marshes had significantly higher rates of surface accretion than the TFFWs, and in the marshes, surface accretion was the primary contributor to elevation change. In contrast, elevation change in TFFWs was more heavily influenced by subsurface processes, such as root zone expansion or compaction, which played an important role in determining resilience of TFFWs to risingsealevel. When root zone contributions were removed statistically from comparisons between relative sea-levelrise and surface elevation change, sites that previously had elevation rate deficits showed a surplus. Therefore, assessments of wetland resilience that do not include subsurface processes will likely misjudge vulnerability to sea-levelrise.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within the Cape Cod National Seashore (CACO). The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. CACO consists of high glacial cliffs, beaches, sand spits, and salt marsh wetlands. The areas most vulnerable to sea-levelrise are those with the lowest regional coastal slopes, geomorphologic types that are susceptible to inundation, and the highest rates of shoreline change. Most of CACO's infrastructure lies on high elevation uplands away from the shore; most high use areas are accessible by foot only. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Padre Island National Seashore in Texas. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, shoreline change rates, mean tidal range and mean significant wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Padre Island National Seashore consists of stable to washover dominated portions of barrier beach backed by wetland, marsh, tidal flat, or grassland. The areas within Padre that are likely to be most vulnerable to sea-levelrise are those with the highest occurrence of overwash and the highest rates of shoreline change.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Dry Tortugas National Park in Florida. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Dry Tortugas National Park (DRTO) consists of relatively stable to washover-dominated portions of carbonate beach and man-made fortification. The areas within Dry Tortugas that are likely to be most vulnerable to sea-levelrise are those with the highest rates of shoreline erosion and the highest wave energy.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Cumberland Island National Seashore in Georgia. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Cumberland Island National Seashore consists of stable to washover-dominated portions of barrier beach backed by wetland, marsh, mudflat and tidal creek. The areas within Cumberland that are likely to be most vulnerable to sea-levelrise are those with the lowest foredune ridge and highest rates of shoreline erosion.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Olympic National Park (OLYM), Washington. The CVI scores the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. The Olympic National Park coast consists of rocky headlands, pocket beaches, glacial-fluvial features, and sand and gravel beaches. The Olympic coastline that is most vulnerable to sea-levelrise are beaches in gently sloping areas.

A coastal vulnerability index (CVI, http://pubs.usgs.gov/of/2004/1020/html/cvi.htm) was used to map relative vulnerability of the coast to future sea-levelrise within Assateague Island National Seashore (ASIS) in Maryland and Virginia. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, shoreline change rates, mean tidal range and mean wave height. Rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Assateague Island consists of stable and washover dominated portions of barrier beach backed by wetland and marsh. The areas within Assateague that are likely to be most vulnerable to sea-levelrise are those with the highest occurrence of overwash and the highest rates of shoreline change.

Strong evidence on climate change underscores the need for actions to reduce the impacts of sea-levelrise. Global mean sealevel may rise 0.18-0.48m by mid-century and 0.5-1.4m by the end of the century. Besides marine inundation, it is largely unrecognized that low-lying coastal areas may also be vulnerable to groundwater inundation, which is localized coastal-plain flooding due to a rise of the groundwater table with sealevel. Measurements of the coastal groundwater elevation and tidal influence in urban Honolulu, Hawaii, allow estimates of the mean water table, which was used to assess vulnerability to groundwater inundation from sea-levelrise. We find that 0.6m of potential sea-levelrise causes substantial flooding, and 1m sea-levelrise inundates 10% of a 1-km wide heavily urbanized coastal zone. The flooded area including groundwater inundation is more than twice the area of marine inundation alone. This has consequences for decision-makers, resource managers and urban planners, and may be applicable to many low-lying coastal areas, especially where groundwater withdrawal is not substantial.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Fire Island National Seashore (FIIS), New York. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. Fire Island consists of stable and washover dominated portions of barrier beach backed by lagoons, tidal wetlands and marsh. The areas most vulnerable to sea-levelrise are those with the highest historic occurrence of overwash and the highest rates of shoreline change. Implementation of large-scale beach nourishment and other coastal engineering alternatives being considered for Fire Island could alter the CVI computed here. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers.

Warming water and melting land ice have raised global mean sealevel 4.5 centimeters (1.7 inches) from 1993 to 2008. But the rise is by no means uniform. This image, created with sea surface height data from the Topex/Poseidon and Jason-1 satellites, shows exactly where sealevel has changed during this time and how quickly these changes have occurred.

It's also a road map showing where the ocean currently stores the growing amount of heat it is absorbing from Earth's atmosphere and the heat it receives directly from the Sun. The warmer the water, the higher the sea surface rises. The location of heat in the ocean and its movement around the globe play a pivotal role in Earth's climate.

Light blue indicates areas in which sealevel has remained relatively constant since 1993. White, red, and yellow are regions where sealevels have risen the most rapidly up to 10 millimeters per year and which contain the most heat. Green areas have also risen, but more moderately. Purple and dark blue show where sealevels have dropped, due to cooler water.

The dramatic variation in sea surface heights and heat content across the ocean are due to winds, currents and long-term changes in patterns of circulation. From 1993 to 2008, the largest area of rapidly risingsealevels and the greatest concentration of heat has been in the Pacific, which now shows the characteristics of the Pacific Decadal Oscillation (PDO), a feature that can last 10 to 20 years or even longer.

In this 'cool' phase, the PDO appears as a horseshoe-shaped pattern of warm water in the Western Pacific reaching from the far north to the Southern Ocean enclosing a large wedge of cool water with low sea surface heights in the eastern Pacific. This ocean/climate phenomenon may be caused by wind-driven Rossby waves. Thousands of kilometers long, these waves move from east to west on either side of the equator changing the distribution of water mass and heat.

Sea-levelrise due to global warming becomes a great matter of concern for global coastal area. Additionally, it has reported in fifth report of IPCC (Intergovernmental Panel on Climate Change) that deglaciation of Greenland ice sheet and Antarctic ice sheet would occur rapidly and enhance sea-levelrise if temperature passes certain "Tipping point". In terms of projecting damage induced by sea-levelrise globally, some previous studies focused on duration until mainly 2100. Furthermore long-term estimations on centuries to millennial climatic response of the ice sheets which are supposed to be triggered within this or next century would be also important to think about future climate and lifestyle in coastal . In this study, I estimated the long term sea-level which take into account the tipping points of Greenland ice sheet (1.4℃) as sum of 4 factors (thermal expansion, glacier and ice cap, Greenland ice sheet, Antarctic ice sheet). The sea-level follows 4 representative concentration pathways up to 3000 obtained through literature reviewing since there were limited available sea-level projections up to 3000. I also estimated a number of affected population lives in coastal area up to 3000 with using the estimated sea-level. The cost for damage, adaptation and mitigation would be also discussed. These estimations would be useful when decision-makers propose policies for construction of dikes and proposing mitigation plans for sustainable future. The result indicates there would be large and relatively rapid increases in both sea-levelrise and coastal exposure if global mean temperature passes the tipping point of Greenland ice sheet. However the tipping points, melting rate and timescale of response are highly uncertain and still discussed among experts. Thus more precise and credible information is required for further accurate estimation of long-term sea-levelrise and population exposure in the future.

Estimations of sealevelrise over the last centuries are mostly based on the rare historical sealevel records from tide gauge stations usually designed for navigational purposes. In this study, we examine the quality of sealevel measurements performed by a mean sealevel gauge operated in Nice from 1887 to 1909 and transferred to the nearby town of Villefranche-sur-Mer in 1913 where it stayed in operation untill 1974. The mean sealevel gauges, called medimaremetres, were invented for geodetic studies and installed in many French ports since the end of the XIX century. By construction, the medimaremetre was connected to the sea through a porous porcelain crucible in order to filter out the tides and higher frequency sealevel oscillations. Ucontrolled properties of the crucible and some systematic errors made the medimaremetre data to be ignored in the current sealevel researches. We demonstrate that the Nice-Villefranche medimaremetre measurements are coherent with two available historical tide gauge records from Marseille and Genova and a new century-scale sealevel series can be build up by combining the medimaremetre data with the those recorded by a tide gauge operating in Nice since the 1980s. We analyse the low frequency variabilities in Marseille, Nice-Villefranche and Genova and get new insights on the decadal sealevel variations in the Ligurian Sea since the end of the XIX century.

Coastal navigation infrastructure may be highly vulnerable to changing climate, including increasing sealevels and altered frequency and intensity of coastal storms. Future gate operations impacted by global sealevelrise will pose unique challenges, especially for structures 50 years and older. Our approach is to estimate future changes in gate operational frequency based on a bootstrapping method to forecast future water levels. A case study will be presented to determine future changes in frequency of operations over the next 100 years. A statistical model in the R programming language was developed to apply future sealevelrise projections using the three sealevelrise scenarios prescribed by USACE Engineer Regulation ER 1100-2-8162. Information derived from the case study will help forecast changes in operational costs caused by increased gate operations and inform timing of decisions on adaptation measures.

Estuaries in tropical Australia have a low sediment yield (about 5-20 tonnes km -2 yr -1). The estuaries formed when rising post-glacial sealevel invaded coastal valleys 7 to 9000 years ago. Geomorphological and stratigraphic data show that mangrove swamps developed on the flooded plains and in some cases their substrate kept pace with the risingsealevel. The bulk of the sediment originated from the sea. When sealevel stabilised, 6000 years ago, the flood plains prograded seaward. The channels now are generally stable and in some cases are inherited from the progradation phase. The response of these estuaries to a sealevelrise may be inferred both from their evolution during post glacial sealevelrise and from hydrodynamics-sedimentological models calibrated against measurements of tidal processes. This was undertaken for Coral Creek, the South Alligator River and the Norman River in north Australia. Modelling indicates that a future sealevelrise will generate changes in the dynamics and channel dimensions which mimic post glacial changes. In the macrotidal South Alligator the floodplain will revert to mangrove, the mouth region will widen and sediment will move upstream and onto the floodplain. In the mesotidal, diurnal Norman the channel will widen throughout and sediment will be transported seawards. In Coral Creek the mangrove will retreat landwards.

Thermal expansion of the ocean in response to warming is an important component of historical sea-levelrise. Observational studies show that the Atlantic and Southern oceans are warming faster than the Pacific Ocean. Here we present simulations using a numerical atmospheric-ocean general circulation model with an interactive carbon cycle to evaluate the impact of carbon emission rates, ranging from 2 to 25 GtC yr-1, on basin-scale ocean heat uptake and sealevel. For simulations with emission rates greater than 5 GtC yr-1, sea-levelrise is larger in the Atlantic than Pacific Ocean on centennial timescales. This basin-scale asymmetry is related to the shorter flushing timescales and weakening of the overturning circulation in the Atlantic. These factors lead to warmer Atlantic interior waters and greater thermal expansion. In contrast, low emission rates of 2 and 3 GtC yr-1 will cause relatively larger sea-levelrise in the Pacific on millennial timescales. For a given level of cumulative emissions, sea-levelrise is largest at low emission rates. We conclude that Atlantic coastal areas may be particularly vulnerable to near-future sea-levelrise from present-day high greenhouse gas emission rates.

Spatial variations of sealevelrise (SLR) can be forced by dynamic processes arising from circulation and variations in temperature and/or salinity, and by static equilibrium processes arising from mass re-distributions changing gravity and the earth's rotation and shape. The sea-level variations can form unique spatial patterns, yet there are very few field observations verifying predicted patterns, or fingerprints. We present evidence of SLR acceleration in a 1,000-km-long hotspot on the North American Atlantic coast north of Cape Hatteras, North Carolina to above Boston, Massachusetts. By using accelerations, or rate differences, sealevel signals that are linear over sub-century records, like the relative sealevel changes arising from vertical land movements of glacial isostatic adjustment, do not affect our results. For a 60-yr regression window (between 1950-1979 and 1980-2009), mean increase in the rate of SLR in the hotspot was 1.97 ± 0.64 mm/yr. (For a 40-yr window, the mean rate increase was 3.80 ± 1.06 mm/yr.) South of Cape Hatteras to Key West, Florida, rate differences for either 60 yr or 40 yr windows were not statistically different from zero (e.g. for 60 yr window: mean= 0.11 ± 0.92 mm/yr). This pattern is similar to a fingerprint of dynamic SLR established by sea-level projections in several climate model studies. Correlations were consistent with accelerated SLR associated with a slowdown of Atlantic Meridional Overturning Current.

Sea-levelrise will change environmental conditions on coral reef flats, which comprise extensive habitats in shallow tropical seas and support a wealth of ecosystem services. Rapid relative sea-levelrise of 0.6 m over a relatively pristine coral reef in Solomon Islands, caused by a subduction earthquake in April 2007, generated a unique opportunity to examine in situ coral reef response to relative sea-levelrise of the magnitude (but not the rate) anticipated by 2100. Extent of live coral was measured from satellite imagery in 2003, 2006, 2009 and 2012. Ecological data were obtained from microatolls and ecological surveys in May 2013. The reef was sampled at 12 locations where dense live hard coral remained absent, remained present or changed from absent to present following subsidence. Ecological data (substratum depth, live coral canopy depth, coral canopy height, substratum suitability, recruitment, diversity and Acropora presence) were measured at each location to identify factors associated with coral response to relative sea-levelrise. Vertical and horizontal proliferation of coral occurred following subsidence. Lateral expansion of live coral, accomplished primarily by branching Acropora spp., resulted in lower diversity in regions which changed composition from pavement to dense live coral following subsidence. Of the ecological factors measured, biotic factors were more influential than abiotic factors; species identity was the most important factor in determining which regions of the reef responded to rapid sea-levelrise. On relatively pristine reef flats under present climatic conditions, rapid relative sea-levelrise generated an opportunity for hard coral to proliferate. However, the species assemblage of the existing reef was important in determining response to sea-level change, by providing previously bare substrate with a source of new coral colonies. Degraded reefs with altered species composition and slower coral growth rates may be less

Despite its purported importance, previous studies of the influence of sea-levelrise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of the sea water intrusion response to sea-levelrise has not been reported. In this study, a simple conceptual framework is used to provide a first-order assessment of sea water intrusion changes in coastal unconfined aquifers in response to sea-levelrise. Two conceptual models are tested: (1) flux-controlled systems, in which ground water discharge to the sea is persistent despite changes in sealevel, and (2) head-controlled systems, whereby ground water abstractions or surface features maintain the head condition in the aquifer despite sea-level changes. The conceptualization assumes steady-state conditions, a sharp interface sea water-fresh water transition zone, homogeneous and isotropic aquifer properties, and constant recharge. In the case of constant flux conditions, the upper limit for sea water intrusion due to sea-levelrise (up to 1.5 m is tested) is no greater than 50 m for typical values of recharge, hydraulic conductivity, and aquifer depth. This is in striking contrast to the constant head cases, in which the magnitude of salt water toe migration is on the order of hundreds of meters to several kilometers for the same sea-levelrise. This study has highlighted the importance of inland boundary conditions on the sea-levelrise impact. It identifies combinations of hydrogeologic parameters that control whether large or small salt water toe migration will occur for any given change in a hydrogeologic variable.

We present a mid to late Holocene sea-level record derived from drilling the New Jersey coast that shows a relatively constant rise of 1.8??mm/yr from ~ 5000 to 500 calibrated calendar years before present (yrBP). This contrasts with previous New Jersey estimates that showed only 0.5??mm/yr rise since 2000??yrBP. Comparison with other Mid-Atlantic sea-level records (Delaware to southern New England) indicates surprising uniformity considering different proximities to the peripheral bulge of the Laurentide ice sheet, with a relative rise throughout the region of ~ 1.7-1.9??mm/yr since ~ 5000??yrBP. This regional sea-levelrise includes both: 1) global sea-level (eustatic) rise; and 2) far-field geoidal subsidence (estimated as ~ 0.8-1.4??mm/yr today) due to removal of the Laurentide ice sheet and water loading. Correcting for geoidal subsidence, the U.S. east coast records suggest a global sea-level (eustatic) rise of ~ 0.4-1.0??mm/yr (with a best estimate of 0.7 ?? 0.3??mm/yr) since 5000??yrBP. Comparison with other records provides a best estimate of pre-anthropogenic global sea-levelrise of < 1.0??mm/yr from 5000 until ~ 200??yrBP. Tide gauge data indicate a 20th century rate of eustatic rise of 1.8??mm/yr, whereas both tide gauge and satellite data suggest an increase in the rate of rise to ~ 3.3??mm/yr from 1993-2006 AD. This indicates that the modern rise (~ 3.3??mm/yr) is significantly higher than the pre-anthropogenic rise (0.7 ?? 0.3??mm/yr). ?? 2008 Elsevier B.V. All rights reserved.

Sea-levelrise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Acceleratedsea-levelrise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-levelrise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-levelrise will also be affected by local ecological context, especially for less sloping beaches. PMID:23861863

Sea-levelrise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Acceleratedsea-levelrise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-levelrise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-levelrise will also be affected by local ecological context, especially for less sloping beaches.

Geoengineering using solar-radiation management (SRM) is gaining interest as a potential strategy to reduce future climate change impacts. Basic physics and past observations suggest that reducing insolation will, on average, cool the Earth. It is uncertain, however, whether SRM can reduce climate change stressors such as sea-levelrise or rates of surface air temperature change. Here we use an Earth system model of intermediate complexity to quantify the possible response of sealevels and surface air temperatures to projected climate forcings and SRM strategies. We find that SRM strategies introduce a potentially strong tension between the objectives to reduce (1) the rate of temperature change and (2) sea-levelrise. This tension arises primarily because surface air temperatures respond faster to radiative forcings than sealevels. Our results show that the forcing required to stop sea-levelrise could cause a rapid cooling with a rate similar to the peak business-as-usual warming rate. Furthermore, termination of SRM was found to produce warming rates up to five times greater than the maximum rates under the business-as-usual CO2 scenario, whereas sea-levelrise rates were only 30% higher. Reducing these risks requires a slow phase-out of many decades and thus commits future generations.

Two degrees of global warming above the preindustrial level is widely suggested as an appropriate threshold beyond which climate change risks become unacceptably high. This "2 °C" threshold is likely to be reached between 2040 and 2050 for both Representative Concentration Pathway (RCP) 8.5 and 4.5. Resulting sealevelrises will not be globally uniform, due to ocean dynamical processes and changes in gravity associated with water mass redistribution. Here we provide probabilistic sealevelrise projections for the global coastline with warming above the 2 °C goal. By 2040, with a 2 °C warming under the RCP8.5 scenario, more than 90% of coastal areas will experience sealevelrise exceeding the global estimate of 0.2 m, with up to 0.4 m expected along the Atlantic coast of North America and Norway. With a 5 °C rise by 2100, sealevel will rise rapidly, reaching 0.9 m (median), and 80% of the coastline will exceed the global sealevelrise at the 95th percentile upper limit of 1.8 m. Under RCP8.5, by 2100, New York may expect rises of 1.09 m, Guangzhou may expect rises of 0.91 m, and Lagos may expect rises of 0.90 m, with the 95th percentile upper limit of 2.24 m, 1.93 m, and 1.92 m, respectively. The coastal communities of rapidly expanding cities in the developing world, and vulnerable tropical coastal ecosystems, will have a very limited time after midcentury to adapt to sealevelrises unprecedented since the dawn of the Bronze Age.

Sealevelrise during the 21st century will have a wide range of effects on coastal environments, human development, and infrastructure in coastal areas. The broad range of complex factors influencing coastal systems contributes to large uncertainties in predicting long-term sealevelrise impacts. Here we explore and demonstrate the capabilities of a Bayesian network (BN) to predict long-term shoreline change associated with sealevelrise and make quantitative assessments of prediction uncertainty. A BN is used to define relationships between driving forces, geologic constraints, and coastal response for the U.S. Atlantic coast that include observations of local rates of relative sealevelrise, wave height, tide range, geomorphic classification, coastal slope, and shoreline change rate. The BN is used to make probabilistic predictions of shoreline retreat in response to different future sealevelrise rates. Results demonstrate that the probability of shoreline retreat increases with higher rates of sealevelrise. Where more specific information is included, the probability of shoreline change increases in a number of cases, indicating more confident predictions. A hindcast evaluation of the BN indicates that the network correctly predicts 71% of the cases. Evaluation of the results using Brier skill and log likelihood ratio scores indicates that the network provides shoreline change predictions that are better than the prior probability. Shoreline change outcomes indicating stability (-1 1 m/yr) was not well predicted. We find that BNs can assimilate important factors contributing to coastal change in response to sealevelrise and can make quantitative, probabilistic predictions that can be applied to coastal management decisions. Copyright ?? 2011 by the American Geophysical Union.

Climate-driven changes in land water storage and their contributions to sealevelrise have been absent from Intergovernmental Panel on Climate Change sealevel budgets owing to observational challenges. Recent advances in satellite measurement of time-variable gravity combined with reconciled global glacier loss estimates enable a disaggregation of continental land mass changes and a quantification of this term. We found that between 2002 and 2014, climate variability resulted in an additional 3200 ± 900 gigatons of water being stored on land. This gain partially offset water losses from ice sheets, glaciers, and groundwater pumping, slowing the rate of sealevelrise by 0.71 ± 0.20 millimeters per year. These findings highlight the importance of climate-driven changes in hydrology when assigning attribution to decadal changes in sealevel.

Secular sealevel trends extracted from tide gauge records of appropriately long duration demonstrate that global sealevel may be rising at a rate in excess of 1 millimeter per year. However, because global coverage of the oceans by the tide gauge network is highly nonuniform and the tide gauge data reveal considerable spatial variability, there has been a well-founded reluctance to interpret the observed secular sealevelrise as representing a signal of global scale that might be related to the greenhouse effect. When the tide gauge data are filtered so as to remove the contribution of ongoing glacial isostatic adjustment to the local sealevel trend at each location, then the individual tide gauge records reveal sharply reduced geographic scatter and suggest that there is a globally coherent signal of strength 2.4 +/- 0.90 millimeters per year that is active in the system. This signal could constitute an indication of global climate warming.

Secular sealevel trends extracted from tide gauge records of appropriately long duration demonstrate that global sealevel may be rising at a rate in excess of 1 millimeter per year. However, because global coverage of the oceans by the tide gauge network is highly nonuniform and the tide gauge data reveal considerable spatial variability, there has been a well-founded reluctance to interpret the observed secular sealevelrise as representing a signal of global scale that might be related to the greenhouse effect. When the tide gauge data are filtered so as to remove the contribution of ongoing glacial isostatic adjustment to the local sealevel trend at each location, then the individual tide gauge records reveal sharply reduced geographic scatter and suggest that there is a globally coherent signal of strength 2.4 {+-} 0.90 millimeters per year that is active in the system. This signal could constitute an indication of global climate warming.

Sealevel changes in the Yangtze River Estuary (YRE) as a result of river discharge are investigated based on the monthly averaged river discharge from 1950 to 2011 at the Datong station. Quantification of the sealevel contribution is made by model computed results and the sealevel rates reported by the China SeaLevel Bulletin (CSLB). The coastal modeling tool, MIKE21, is used to establish a depth-averaged hydrodynamic model covering the YRE and Hangzhou Bay. The model is validated with the measured data. Multi-year monthly river discharges are statistically calculated based on the monthly river discharges at Datong station from 1950 to 2011. The four characteristic discharges (frequency of 75%, 50% and 25%, and multi-year monthly) and month-averaged river discharge from 1950 to 2011 are used to study the seasonal and long-term changes of sealevel. The computed sealevel at the Dajishan and Lvsi stations are used to study the multi-time scale structure of periodic variation in different time scale of river discharge series. The results reveal that (1) the sealevelrises as the river discharge increases, and its amplification decreases from upstream to the offshore. (2) The sealevel amplification on the south coast is greater than that on the north coast. When river discharge increases by 20,000 m3/s, the sealevel will increase by 0.005-0.010 m in most of Hangzhou Bay. (3) The sealevel at the Dajishan station, influenced by river discharge, increased 0.178 mm/y from 1980 to 2011. Correspondingly, the sealevel rose at a rate of 2.6-3.0 mm/y during the same period. These values were provided by the CSLB. The increase in sealevel (1980-2011) at the Dajishan station caused by river discharge is 6.8-8.9% of the total increase in sealevel. (4) The 19-20 year dominant nodal cycle of sealevel at the Dajishan and Lvsi stations is in accord with 18.6 year nodal cycle of main tidal constituents on Chinese coasts. It implies that the sea-level change period on the

To test a hypothesized faster-than-global sealevelacceleration along the mid-Atlantic United States, I construct a Gaussian process model that decomposes tide gauge data into short-term variability and longer-term trends, and into globally coherent, regionally coherent, and local components. While tide gauge records indicate a faster-than-global increase in the rate of mid-Atlantic U.S. sealevelrise beginning ˜1975, this acceleration could reflect either the start of a long-term trend or ocean dynamic variability. The acceleration will need to continue for ˜2 decades before the rate of increase of the sealevel difference between the mid-Atlantic and southeastern U.S. can be judged as very likely unprecedented by 20th century standards. However, the difference is correlated with the Atlantic Multidecadal Oscillation, North Atlantic Oscillation, and Gulf Stream North Wall indices, all of which are currently within the range of past variability.

Climate change depends on the increase of several different atmospheric pollutants. While long term global warming will be determined mainly by carbon dioxide, warming in the next few decades will depend to a large extent on short lived climate pollutants (SLCP). Reducing emissions of SLCPs could contribute to lower the global mean surface temperature by 0.5 °C already by 2050 (Shindell et al. 2012). Furthermore, the warming effect of one of the most potent SLCPs, black carbon (BC), may have been underestimated in the past. Bond et al. (2013) presents a new best estimate of the total BC radiative forcing (RF) of 1.1 W/m2 (90 % uncertainty bounds of 0.17 to 2.1 W/m2) since the beginning of the industrial era. BC is however never emitted alone and cooling aerosols from the same sources offset a majority of this RF. In the wake of calls for mitigation of SLCPs it is important to study other aspects of the climate effect of SLCPs. One key impact of climate change is sea-levelrise (SLR). In a recent study, the effect of SLCP mitigation scenarios on SLR is examined. Hu et al (2013) find a substantial effect on SLR from mitigating SLCPs sharply, reducing SLR by 22-42% by 2100. We choose a different approach focusing on emission pulses and analyse a metric based on sealevelrise so as to further enlighten the SLR consequences of SLCPs. We want in particular to understand the time dynamics of SLR impacts caused by SLCPs compared to other greenhouse gases. The most commonly used physical based metrics are GWP and GTP. We propose and evaluate an additional metric: The global sea-levelrise potential (GSP). The GSP is defined as the sealevelrise after a time horizon caused by an emissions pulse of a forcer to the sealevelrise after a time horizon caused by an emissions pulse of a CO2. GSP is evaluated and compared to GWP and GTP using a set of climate forcers chosen to cover the whole scale of atmospheric perturbation life times (BC, CH4, N2O, CO2 and SF6). The study

Sea-levelrise is becoming an ever-increasing problem in California. Sea-level is expected to rise significantly in the next 100 years, which will raise flood elevations in coastal communities. This will be an issue for private homeowners, businesses, and the state. One study suggests that Venice Beach could lose a total of at least $440 million in tourism spending and tax dollars from flooding and beach erosion if sealevelrises 1.4 m by 2100. In addition, several airports, such as San Francisco International Airport, are located in coastal regions that have flooded in the past and will likely be flooded again in the next 30 years, but sea-levelrise is expected to worsen the effects of flooding in the coming decades It is vital for coastal communities to understand the risks associated with sea-levelrise so that they can plan to adapt to it. By obtaining accurate LiDAR elevation data from the NOAA Digital Coast Website (http://csc.noaa.gov/dataviewer/?keyword=lidar#), we can create flood maps to simulate sealevelrise and flooding. The data are uploaded to ArcGIS and contour lines are added for different elevations that represent future coastlines during 100-year flooding. The following variables are used to create the maps: 1. High-resolution land surface elevation data - obtained from NOAA 2. Local mean high water level - from USGS 3. Local 100-year flood water level - from the Pacific Institute 4. Sea-levelrise projections for different future dates (2030, 2050, and 2100) - from the National Research Council The values from the last three categories are added to represent sea-levelrise plus 100-year flooding. These values are used to make the contour lines that represent the projected flood elevations, which are then exported as KML files, which can be opened in Google Earth. Once these KML files are made available to the public, coastal communities will gain an improved understanding of how flooding and sea-levelrise might affect them in the future

Sea-levelrise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves1, 2. Mangrove forests have the capacity to keep pace with sea-levelrise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth3. The Indo-Pacific region holds most of the world’s mangrove forests4, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers5. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-levelrise6, 7. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments8, 9, 10. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-levelrise, but for 69 per cent of our study sites the current rate of sea-levelrise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

The mean sealevel has been projected to rise in the 21st century as a result of global warming. Such projections of sealevel change depend on estimated future greenhouse emissions and on differing models, but model-average results from a mid-range scenario (A1B) suggests a 0.387-m rise by 2100 (refs 1, 2). The largest contributions to sealevelrise are estimated to come from thermal expansion (0.288 m) and the melting of mountain glaciers and icecaps (0.106 m), with smaller inputs from Greenland (0.024 m) and Antarctica (- 0.074 m). Here we apply a melt model and a geometric volume model to our lower estimate of ice volume and assess the contribution of glaciers to sealevelrise, excluding those in Greenland and Antarctica. We provide the first separate assessment of melt contributions from mountain glaciers and icecaps, as well as an improved treatment of volume shrinkage. We find that icecaps melt more slowly than mountain glaciers, whose area declines rapidly in the 21st century, making glaciers a limiting source for ice melt. Using two climate models, we project sealevelrise due to melting of mountain glaciers and icecaps to be 0.046 and 0.051 m by 2100, about half that of previous projections.

Sea-levelrise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-levelrise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds most of the world's mangrove forests, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-levelrise. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-levelrise, but for 69 per cent of our study sites the current rate of sea-levelrise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

Sea-levelrise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-levelrise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds most of the world's mangrove forests, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-levelrise. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-levelrise, but for 69 per cent of our study sites the current rate of sea-levelrise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

Salt marshes buffer coastlines and provide critical ecosystem services from storm protection to food provision. Worldwide, these ecosystems are in danger of disappearing if they cannot increase elevation at rates that match sea-levelrise. However, the magnitude of loss to be expected is not known. A synthesis of existing records of salt marsh elevation change was conducted in order to consider the likelihood of their future persistence. This analysis indicates that many salt marshes did not keep pace with sea-levelrise in the past century and kept pace even less well over the past two decades. Salt marshes experiencing higher local sea-levelrise rates were less likely to be keeping pace. These results suggest that sea-levelrise will overwhelm most salt marshes' capacity to maintain elevation. Under the most optimistic IPCC emissions pathway, 60% of the salt marshes studied will be gaining elevation at a rate insufficient to keep pace with sea-levelrise by 2100. Without mitigation of greenhouse gas emissions this potential loss could exceed 90%, which will have substantial ecological, economic, and human health consequences.

Increasing concern over sea-levelrise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-levelrise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-levelrise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-levelrise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-levelrise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-levelrise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus. Under mid and high sea-levelrise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sealevel. Our modeling assumed no marsh migration upslope due to human

The University of Colorado Boulder in collaboration with the National Park Service has undertaken the task of compiling sealevel change and storm surge data for 105 coastal parks. The aim of our research is to highlight areas of the park system that are at increased risk of rapid inundation as well as periodic flooding due to sealevelrise and storms. This research will assist park managers and planners in adapting to climate change. The National Park Service incorporates climate change data into many of their planning documents and is willing to implement innovative coastal adaptation strategies. Events such as Hurricane Sandy highlight how impacts of coastal hazards will continue to challenge management of natural and cultural resources and infrastructure along our coastlines. This poster will discuss the current status of this project. We discuss the impacts of Hurricane Sandy as well as the latest sealevelrise and storm surge modeling being employed in this project. In addition to evaluating various drivers of relative sea-level change, we discuss how park planners and managers also need to consider projected storm surge values added to sea-levelrise magnitudes, which could further complicate the management of coastal lands. Storm surges occurring at coastal parks will continue to change the land and seascapes of these areas, with the potential to completely submerge them. The likelihood of increased storm intensity added to increasing rates of sea-levelrise make predicting the reach of future storm surges essential for planning and adaptation purposes. The National Park Service plays a leading role in developing innovative strategies for coastal parks to adapt to sea-levelrise and storm surge, whilst coastal storms are opportunities to apply highly focused responses.

Sea-levelrise will affect coastal species worldwide, but models that aim to predict these effects are typically based on simple measures of sealevel that do not capture its inherent complexity, especially variation over timescales shorter than 1 year. Coastal species might be most affected, however, by floods that exceed a critical threshold. The frequency and duration of such floods may be more important to population dynamics than mean measures of sealevel. In particular, the potential for changes in the frequency and duration of flooding events to result in nonlinear population responses or biological thresholds merits further research, but may require that models incorporate greater resolution in sealevel than is typically used. We created population simulations for a threatened songbird, the saltmarsh sparrow (Ammodramus caudacutus), in a region where sealevel is predictable with high accuracy and precision. We show that incorporating the timing of semidiurnal high tide events throughout the breeding season, including how this timing is affected by mean sea-levelrise, predicts a reproductive threshold that is likely to cause a rapid demographic shift. This shift is likely to threaten the persistence of saltmarsh sparrows beyond 2060 and could cause extinction as soon as 2035. Neither extinction date nor the population trajectory was sensitive to the emissions scenarios underlying sea-level projections, as most of the population decline occurred before scenarios diverge. Our results suggest that the variation and complexity of climate-driven variables could be important for understanding the potential responses of coastal species to sea-levelrise, especially for species that rely on coastal areas for reproduction.

Future sealevelrise (SL), which represents today one of the major threats that are caused by climate change, will not be uniform. Regional differences are crucial for 40% of the world population, which is located in the coastal zone. To explore the mechanisms linking regional SL to climate variables is very important in order to provide reliable future projections. This study focuses on two semi-enclosed basins, the Adriatic and Baltic Sea and investigates the deviation of their SL from the mean global value. In fact, past deviations of the SL of these two basins from the global value have been observed and can be attributed to large scale factors (such as teleconnections) and regional factors, such as the inverse barometric effect, the wind stress, the thermosteric and halosteric effects. The final goal of this work is to assess to which extent the Adriatic and Baltic SL will depart from the mean global value in the next decades and at the end of 21st century. This is achieved by analyzing deviations of the mean SL of the Baltic and Adriatic Sea from the global mean SL during the 20th century and investigating which factors can explain such deviations. A multivariate linear regression model is built and used to describe the link between three large scale climate variables which are used as predictors (mean sealevel pressure, surface air temperature and precipitation), and the regional SL deviation (the predictand), computed as the difference between the regional and the global SL. At monthly scale this linear regression model provides a good reconstruction of the past variability in the cold season during which it explains 60%-70% of the variance. Summer reconstruction is substantially less successful and it represents presently the main limit of the model skill. This linear regression model, forced by predictors extracted from CMIP5 multi-model simulations, is used to provide projections of SL in the Adriatic and Baltic Sea. On the basis of the projections

The rate of twentieth-century global sealevelrise and its causes are the subjects of intense controversy. Most direct estimates from tide gauges give 1.5-2.0 mm yr(-1), whereas indirect estimates based on the two processes responsible for global sealevelrise, namely mass and volume change, fall far below this range. Estimates of the volume increase due to ocean warming give a rate of about 0.5 mm yr(-1) (ref. 8) and the rate due to mass increase, primarily from the melting of continental ice, is thought to be even smaller. Therefore, either the tide gauge estimates are too high, as has been suggested recently, or one (or both) of the mass and volume estimates is too low. Here we present an analysis of sealevel measurements at tide gauges combined with observations of temperature and salinity in the Pacific and Atlantic oceans close to the gauges. We find that gauge-determined rates of sealevelrise, which encompass both mass and volume changes, are two to three times higher than the rates due to volume change derived from temperature and salinity data. Our analysis supports earlier studies that put the twentieth-century rate in the 1.5-2.0 mm yr(-1) range, but more importantly it suggests that mass increase plays a larger role than ocean warming in twentieth-century global sealevelrise.

Removal of water from terrestrial subsurface storage is a natural consequence of groundwater withdrawals, but global depletion is not well characterized. Cumulative groundwater depletion represents a transfer of mass from land to the oceans that contributes to sea-levelrise. Depletion is directly calculated using calibrated groundwater models, analytical approaches, or volumetric budget analyses for multiple aquifer systems. Estimated global groundwater depletion during 1900–2008 totals ~4,500 km3, equivalent to a sea-levelrise of 12.6 mm (>6% of the total). Furthermore, the rate of groundwater depletion has increased markedly since about 1950, with maximum rates occurring during the most recent period (2000–2008), when it averaged ~145 km3/yr (equivalent to 0.40 mm/yr of sea-levelrise, or 13% of the reported rate of 3.1 mm/yr during this recent period).

In a recent article (Eos, Trans., AGU, February 8, 2000, p.55), Leatherman et al. [2000] state that they have confirmed an association between sea-levelrise and coastal erosion. Applying their results to the New Jersey, Delaware, and Maryland coasts and using a projected sea-levelrise, the authors predict that by 2050 the shoreline will recede 60 m, about two times the average beach width. However, Leatherman et al. [2000] have not convincingly quantified a relationship between sea-levelrise and shoreline erosion.We do not agree with their rationale for subsetting their data, and they have not considered other explanations for a background erosion along the U.S. east coast. Furthermore, their future projections are not supported by their analyses.

Prydz Bay is one of the largest embayments on the East Antarctic coast and it is the discharge point for approximately 16% of the East Antarctic Ice Sheet. Geological constraints on the regional ice sheet history include evidence of past relative sea-level change at three sites; the Vestfold Hills, Rauer Islands and Larsemann Hills. In this paper we compile updated regional relative sea-level data from these sites. We compare these with a suite of relative sea-level predictions derived from glacial isostatic adjustment models and discuss the significance of departures between the models and the field evidence. The compiled geological data extend the relative sea-level curve for this region to 11,258 cal yr BP and include new constraints based on abandoned penguin colonies, new isolation basin data in the Vestfold Hills, validation of a submarine relative sea-level constraint in the Rauer Islands and recalibrated radiocarbon ages at all sites dating from 12,728 cal yr BP. The field data show rapid increases in rates of relative sealevelrise of 12-48 mm/yr between 10,473 (or 9678) and 9411 cal yr BP in the Vestfold Hills and of 8.8 mm/yr between 8882 and 8563 cal yr BP in the Larsemann Hills. The relative sea-level high stands of ≥ 8.8 m from 9411 to after 7564 cal yr BP (Vestfold Hills) and ≥ 8 m at 8563 and 7066 cal yr BP (Larsemann Hills) are over-predicted by some of the glacial isostatic adjustment models considered here, suggesting that assumptions relating to the magnitude and timing of regional ice loss since the Last Glacial Maximum may need revising. In the Vestfold Hills and Rauer Islands the final deglacial sea-levelrise was almost exactly cancelled out by local rebound between 9411 and 5967 cal yr BP and this was followed by a near exponential decay in relative sea-level. In the Larsemann Hills the sea-level data suggest that the rate of ice retreat in this region was not uniform throughout the Holocene. Swath bathymetric surveys of the benthic

The sealevels of Kiribati have been stable over the last few decades, as elsewhere in the world. The Australian government funded Pacific SeaLevel Monitoring (PSLM) project has adjusted sealevel records to produce an unrealistic rising trend. Some information has been hidden or neglected, especially from sources of different management. The measured monthly average mean sealevels suffer from subsidence or manipulation resulting in a tilting from the about 0 (zero) mm/year of nearby tide gauges to 4 (four) mm/year over the same short time window. Real environmental problems are driven by the increasing local population leading to troubles including scarcity of water, localized sinking and localised erosion.

To study the response of coastal wetlands to climate change, assess the impacts of climate change on the coastal wetlands and formulate feasible and practical mitigation strategies are the important prerequisite for securing coastal ecosystems. In this paper, the possible impacts of sealevelrise caused by climate change on the coastal wetlands in the Yangtze Estuary were analyzed by the Source-Pathway-Receptor-Consequence (SPRC) model and IPCC definition on the vulnerability. An indicator system for vulnerability assessment was established, in which sea-levelrise rate, subsidence rate, habitat elevation, inundation threshold of habitat and sedimentation rate were selected as the key indicators. A quantitatively spatial assessment method based on the GIS platform was established by quantifying each indicator, calculating the vulnerability index and grading the vulnerability index for the assessment of coastal wetlands in the Yangtze Estuary under the scenarios of sea-levelrise. The vulnerability assessments on the coastal wetlands in the Yangtze Estuary in 2030 and 2050 were performed under two sea-levelrise scenarios (the present sea-levelrise trend over recent 30 years and IPCC A1F1 scenario). The results showed that with the projection in 2030 under the present trend of sea-levelrise (0.26 cm x a(-1)), 6.6% and 0.1% of the coastal wetlands were in the low and moderate vulnerabilities, respectively; and in 2050, 9.8% and 0.2% of the coastal wetlands were in low and moderate vulnerabilities, respectively. With the projection in 2030 under the A1F1 scenario (0.59 cm x a(-1)), 9.0% and 0.1% of the coastal wetlands were in the low and moderate vulnerabilities, respectively; and in 2050, 9.5%, 1.0% and 0.3% of the coastal wetlands were in the low, moderate and high vulnerabilities, respectively.

The northern Gulf of Mexico coast of the United States has been identified as highly vulnerable to sea-levelrise, based on a combination of physical and societal factors. Vulnerability of human populations and infrastructure to projected increases in sealevel is a critical area of uncertainty for communities in the extremely low-lying and flat northern gulf coastal zone. A rapidly growing population along some parts of the northern Gulf of Mexico coastline is further increasing the potential societal and economic impacts of projected sea-levelrise in the region, where observed relative rise rates range from 0.75 to 9.95 mm per year on the Gulf coasts of Texas, Louisiana, Mississippi, Alabama, and Florida. A 1-m elevation threshold was chosen as an inclusive designation of the coastal zone vulnerable to relative sea-levelrise, because of uncertainty associated with sea-levelrise projections. This study applies a Coastal Economic Vulnerability Index (CEVI) to the northern Gulf of Mexico region, which includes both physical and economic factors that contribute to societal risk of impacts from risingsealevel. The economic variables incorporated in the CEVI include human population, urban land cover, economic value of key types of infrastructure, and residential and commercial building values. The variables are standardized and combined to produce a quantitative index value for each 1-km coastal segment, highlighting areas where human populations and the built environment are most at risk. This information can be used by coastal managers as they allocate limited resources for ecosystem restoration, beach nourishment, and coastal-protection infrastructure. The study indicates a large amount of variability in index values along the northern Gulf of Mexico coastline, and highlights areas where long-term planning to enhance resiliency is particularly needed.

Low-relief deltaic coastal plains commonly experience land loss because of the cumulative effects of natural and human-induced processes. Although it is difficult to separate the individual factors within the overall process, interplay between these factors can result in a rate of relative sealevelrise greater than the natural rate of coastal-plain aggradation that causes land loss. Between 1956 and 1978, about 11,400 and 2,490 ha of marsh were lost in east Texas and Mississippi, respectively. Louisiana's loss was 18,755 ha. Relative sealevelrise over the last 65 yr has averaged 0.23 cm/yr in the Gulf and as much as 1-1.5 cm/yr in the delta plain. The Environmental Protection Agency predicts the rate of sealevelrise to increase over the next century. Rates of relative sealevelrise for the Gulf of Mexico are expected to increase from 0.23-1.5 cm/yr to 0.6-3.7 cm/yr. The current rate of relative sealevelrise and land loss in the subsiding Mississippi delta is a response that can be expected for many US coastal areas over the next century. With the predicted change, the Mississippi River delta complex will experience dramatically increased rates of land loss. Isles Dernieres will disappear by the year 2000, and Plaquemines and Terrebonne marshes will be gone between 2020 and 2080. Based on the lowest predicted sealevelrise rate, by the year 2100, the delta plain could be reduced from 150.9 {times} 10{sup 3} ha to 29.8 x 10{sup 3} ha or to 4.9 {times} 10{sup 3} ha if calculations are based on the highest rate.

Glaciers and ice caps (GICs) are important contributors to present-day global mean sealevelrise. Most previous global mass balance estimates for GICs rely on extrapolation of sparse mass balance measurements representing only a small fraction of the GIC area, leaving their overall contribution to sealevelrise unclear. Here we show that GICs, excluding the Greenland and Antarctic peripheral GICs, lost mass at a rate of 148 ± 30 Gt yr(-1) from January 2003 to December 2010, contributing 0.41 ± 0.08 mm yr(-1) to sealevelrise. Our results are based on a global, simultaneous inversion of monthly GRACE-derived satellite gravity fields, from which we calculate the mass change over all ice-covered regions greater in area than 100 km(2). The GIC rate for 2003-2010 is about 30 per cent smaller than the previous mass balance estimate that most closely matches our study period. The high mountains of Asia, in particular, show a mass loss of only 4 ± 20 Gt yr(-1) for 2003-2010, compared with 47-55 Gt yr(-1) in previously published estimates. For completeness, we also estimate that the Greenland and Antarctic ice sheets, including their peripheral GICs, contributed 1.06 ± 0.19 mm yr(-1) to sealevelrise over the same time period. The total contribution to sealevelrise from all ice-covered regions is thus 1.48 ± 0.26 mm (-1), which agrees well with independent estimates of sealevelrise originating from land ice loss and other terrestrial sources.

Understanding and predicting the response of salt-marsh bio-geomorphic systems to changes in the rate of sealevelrise and sediment supply is an issue of paramount importance due to the crucial role exerted by salt marshes within the tidal landscape. Salt-marsh platforms, in fact, buffer coastlines against storms, filter nutrients and pollutants from tidal waters, provide nursery areas for coastal biota, and serve as a sink for organic carbon. Observations of marsh degradation worldwide and the acceleration in the rate of global sealevelrise highlight the importance of improving our understanding of the chief processes which control salt-marsh response to current natural climate changes and to the effects of variations in sediment supply. The results of our analytical model of salt-marsh bio-morphodynamic evolution in the vertical plane, accounting for two-way interactions between ecological and geomorphological processes, show that marshes are more resilient to a step decrease in the rate of relative sealevelrise rather than to a step increase of the same magnitude. Interestingly, marshes respond more rapidly to an increase in sediment load or vegetation productivity, rather than to a decrease (of the same amount) in sediment load or vegetation productivity. Model results also suggest that marsh stability is positively correlated with tidal range: marshes with high tidal ranges respond more slowly to changes in the environmental forcings and therefore are less likely to be affected by perturbations than their counterparts in low tidal ranges. Finally, the model suggests that, in the case of a oscillating rate of sealevelrise, marsh stratigraphy will be unable to fully record short term fluctuations in relative mean sealevel, whereas it will be able to capture long term fluctuations particularly in sediment rich, microtidal settings.

The southern Chesapeake Bay region is experiencing land subsidence and rising water levels due to global sea-levelrise; land subsidence and rising water levels combine to cause relative sea-levelrise. Land subsidence has been observed since the 1940s in the southern Chesapeake Bay region at rates of 1.1 to 4.8 millimeters per year (mm/yr), and subsidence continues today. This land subsidence helps explain why the region has the highest rates of sea-levelrise on the Atlantic Coast of the United States. Data indicate that land subsidence has been responsible for more than half the relative sea-levelrise measured in the region. Land subsidence increases the risk of flooding in low-lying areas, which in turn has important economic, environmental, and human health consequences for the heavily populated and ecologically important southern Chesapeake Bay region. The aquifer system in the region has been compacted by extensive groundwater pumping in the region at rates of 1.5- to 3.7-mm/yr; this compaction accounts for more than half of observed land subsidence in the region. Glacial isostatic adjustment, or the flexing of the Earth’s crust in response to glacier formation and melting, also likely contributes to land subsidence in the region.

Climate change is expected to both impact sealevelrise as well as flooding. Our study focuses on the combined effect of climate change on upper catchment precipitation as well as on sea-levelrise at the river mouths and the impact this will have on river flooding both at the coast and further upstream. We concentrate on the eight catchments of the Amazonas, Congo, Orinoco, Ganges/Brahmaputra/Meghna, Mississippi, St. Lawrence, Danube and Niger rivers. To assess the impact of climate change, upper catchment precipitation as well as monthly mean thermosteric sea-levelrise at the river mouth outflow are taken from the four CCSM4 1° 20th Century ensemble members as well as from six CCSM4 1° ensemble members for the RCP scenarios RCP8.5, 6.0, 4.5 and 2.6. Continuous daily time series for average catchment precipitation and discharge are available for each of the catchments. To arrive at a future discharge time series, we used these observations to develop a simple statistical hydrological model which can be applied to the modelled future upper catchment precipitation values. The analysis of this surrogate discharge time series alone already yields significant changes in flood return levels as well as flood duration. Using the geometry of the river channel, the backwater effect of sea-levelrise is incorporated in our analysis of both flood frequencies and magnitudes by calculating the effective additional discharge due to the increase in water level at the river mouth outflow, as well as its tapering impact upstream. By combining these effects, our results focus on the merged impact of changes in extreme precipitation with increases in river height due to sea-levelrise at the river mouths. Judging from our preliminary results, the increase in effective discharge due to sea-levelrise cannot be neglected when discussing late 21st century flooding in the respective river basins. In particular, we find that especially in countries with low elevation gradient, flood

Understanding the consequence of sea-levelrise for coastal cities has long lead times and huge political implications. Civilisation has emerged and developed during a period of several thousand years during which in geological terms sealevel has been unusually stable. We have now moved out of this period raising important challenges for the future. In 2005 there were 136 coastal cities with a population exceeding one million people and a collective population of 400 million people. All these cities are threatened by flooding from the sea to varying degrees and these risks are increasing due to growing exposure (people and assets), risingsealevels due to climate change, and in some cities, significant coastal subsidence due to human agency (drainage and groundwater withdrawals from susceptible soils). City abandonment due to sea-levelrise is widely discussed in the media, but most of the discussion is speculative. The limits to adaptation and abandonment of cities are not predictable in a formal sense - while the rise in mean sealevel raises the likelihood of a catastrophic flood, extreme events are what cause damage and trigger a response, be it abandonment or a defence upgrade. Several types of potential adaptation limits can be recognised: (1) physical/engineering limits; (2) economic/financial limits; and (3) socio-political limits. The latter two types of limits are much less understood, and yet issues such as loss of confidence rather than a simple engineering failure may be instrumental in the future of a coastal city. There are few studies which quantify the sea-levelrise threshold at which cities will be challenged, especially for large rises exceeding a metre or more. Exceptions include London and the Thames Estuary and the Amsterdam and Rotterdam (the Netherlands) where adaptation to a rise of sealevel of up to 4 m or more appears feasible. This lack of knowledge on sea-levelrise thresholds for coastal cities is of concern, and similar

This special issue of CLIVAR Exchanges is devoted to presenting a selection of the science contributed by both speakers and poster presenters at the CLIVAR Workshop on SeaLevelRise, Ocean/Ice Shelf Interactions and Ice Sheets at CSIRO Marine and Atmospheric Research in Hobart, Australia, on 18-20 February 2013. The workshop brought together leading international scientists and early-career researchers from the ocean, ice-sheet, ice-shelf, and sea-levelrise modelling and observational communities to explore the state-of-science and emerging pathways for development of the next generation of coupled climate models.

Unmitigated greenhouse gas emissions may increase global mean sea-level by about 1 meter during this century. Such elevation of the mean sea-level enhances the risk of flooding of coastal areas. We compute the power capacity that is currently out-of-reach of a 100-year coastal flooding but will be exposed to such a flood by the end of the century for different US states, if no adaptation measures are taken. The additional exposed capacity varies strongly among states. For Delaware it is 80% of the mean generated power load. For New York this number is 63% and for Florida 43%. The capacity that needs additional protection compared to today increases by more than 250% for Texas, 90% for Florida and 70% for New York. Current development in power plant building points towards a reduced future exposure to sea-levelrise: proposed and planned power plants are less exposed than those which are currently operating. However, power plants that have been retired or canceled were less exposed than those operating at present. If sea-levelrise is properly accounted for in future planning, an adaptation to sea-levelrise may be costly but possible.

Global sealevelrise has the potential to become one of the most costly and least well predicted impacts of human caused climate change. Unlike global surface temperature, the spread of possible scenarios (as little as 1 foot and as much as 6 feet by 2100) is not due to uncertainty about future rates of greenhouse gas emissions, but rather by a fundamental lack of knowledge about how the major ice sheets will behave in a warming climate. Clearly improved projections of sealevelrise should become a major research priority in the next decade. At present, controversial techniques based on comparison with historical analogs and rates of recent warming and sealevelrise are often used to create projections for the 21st Century. However, many in the scientific community feel that reliable projections must be based on a sound knowledge of the physics governing sealevelrise, and particularly ice sheet behavior. In particular, large portions of the West Antarctic Ice Sheet and parts of the Greenland Ice Sheet rest on solid earth that sits below sealevel. These regions may be threatened, not by atmospheric warming or changes in precipitation, but rather by direct forcing from the ocean. Fledgling efforts to understand these ocean ice interactions are already underway, as are efforts to make improved models of ice sheet behavior. However a great deal of work is still needed before widely accepted projections of sealevelrise become a reality. This paper will highlight the hurdles to making such projections today and suggest ways forward in this critical area of research.

Sealevelrise is rapidly turning into major issues among our community and all levels of the government are working to develop responses to ensure these matters are given the uttermost attention in all facets of planning. It is more interesting to understand and investigate the present day sealevel variation due its potential impact, particularly on our national geodetic vertical datum. To determine present day sealevel variation, it is vital to consider both in-situ tide gauge and remote sensing measurements. This study presents an effort to quantify the sealevelrise rate and magnitude over Peninsular Malaysia using tide gauge and multi-mission satellite altimeter. The time periods taken for both techniques are 32 years (from 1984 to 2015) for tidal data and 23 years (from 1993 to 2015) for altimetry data. Subsequently, the impact of sealevelrise on Peninsular Malaysia Geodetic Vertical Datum (PMGVD) is evaluated in this study. the difference between MSL computed from 10 years (1984 - 1993) and 32 years (1984 - 2015) tidal data at Port Kelang showed that the increment of sealevel is about 27mm. The computed magnitude showed an estimate of the long-term effect a change in MSL has on the geodetic vertical datum of Port Kelang tide gauge station. This will help give a new insight on the establishment of national geodetic vertical datum based on mean sealevel data. Besides, this information can be used for a wide variety of climatic applications to study environmental issues related to flood and global warming in Malaysia.

As sealevelrises, a barrier island will respond either by migrating landward across the underlying substrate to higher elevations or by disintegrating if there is no longer sufficient sand volume and relief above sealevel to prevent inundation during storms. Using the morphological-behavior model GEOMBEST, we investigate the sea-levelrise response of a complex coastal environment to changes in variety of factors, thus yielding insights into barrier island evolution. Our base case is a simplified Holocene run which simulates a possible scenario for the evolution of a 25-km stretch of the North Carolina Outer Banks over the last 8500 years. Varying one parameter at a time, we explore the degree to which changes in sea-levelrise rate, sediment supply/loss rate, offshore limits to sediment transport, substrate erodibility, substrate composition and depth- dependent response rate produce changes in average landward barrier island migration rate, average depth of substrate erosion, and final barrier island volume. As expected, sensitivity analyses reveal that within the range of possible values for the North Carolina coast, sea-levelrise rate, followed by sediment supply rate, is the most important factor in determining barrier island response to sea-levelrise. More surprisingly, the analyses in aggregate indicate that barrier island evolution is highly sensitive to the range of substrate slopes encountered throughout landward migration (i.e., the slope history); as a barrier encounters a continually changing substrate slope, island volume constantly changes, moving toward equilibrium with the current average slope. Through this process, steeper average slope histories produce smaller barrier islands while shallower average slope histories produce larger barrier islands. In both cases, secondary effects on substrate erosion depth and migration rate also result. Notably, similar geometric effects explain an insensitivity of simulation results to changes in offshore

Digital elevation models of the Northern and Southern Patagonia Icefields of South America generated from the 2000 Shuttle Radar Topography Mission were compared with earlier cartography to estimate the volume change of the largest 63 glaciers. During the period 1968/1975-2000, these glaciers lost ice at a rate equivalent to a sealevelrise of 0.042 +/- 0.002 millimeters per year. In the more recent years 1995-2000, average ice thinning rates have more than doubled to an equivalent sealevelrise of 0.105 +/- 0.011 millimeters per year. The glaciers are thinning more quickly than can be explained by warmer air temperatures and decreased precipitation, and their contribution to sealevel per unit area is larger than that of Alaska glaciers.

During the last interglacial period (the Eemian), global sealevel was at least three metres, and probably more than five metres, higher than at present. Complete melting of either the West Antarctic ice sheet or the Greenland ice sheet would today raise sealevels by 6-7 metres. But the high sealevels during the last interglacial period have been proposed to result mainly from disintegration of the West Antarctic ice sheet, with model studies attributing only 1-2 m of sea-levelrise to meltwater from Greenland. This result was considered consistent with ice core evidence, although earlier work had suggested a much reduced Greenland ice sheet during the last interglacial period. Here we reconsider the Eemian evolution of the Greenland ice sheet by combining numerical modelling with insights obtained from recent central Greenland ice-core analyses. Our results suggest that the Greenland ice sheet was considerably smaller and steeper during the Eemian, and plausibly contributed 4-5.5 m to the sea-level highstand during that period. We conclude that the high sealevel during the last interglacial period most probably included a large contribution from Greenland meltwater and therefore should not be interpreted as evidence for a significant reduction of the West Antarctic ice sheet.

Tidal marshes maintain elevation relative to sealevel through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of acceleratedsea-levelrise. Uncertainties exist about tidal marsh resiliency to acceleratedsea-levelrise, reduced sediment supply, reduced plant productivity under increased inundation, and limited upland habitat for marsh migration. We examined marsh resiliency under these uncertainties using the Marsh Equilibrium Model, a mechanistic, elevation-based soil cohort model, using a rich data set of plant productivity and physical properties from sites across the estuarine salinity gradient. Four tidal marshes were chosen along this gradient: two islands and two with adjacent uplands. Varying century sea-levelrise (52, 100, 165, 180 cm) and suspended sediment concentrations (100%, 50%, and 25% of current concentrations), we simulated marsh accretion across vegetated elevations for 100 years, applying the results to high spatial resolution digital elevation models to quantify potential changes in marsh distributions. At low rates of sea-levelrise and mid-high sediment concentrations, all marshes maintained vegetated elevations indicative of mid/high marsh habitat. With century sea-levelrise at 100 and 165 cm, marshes shifted to low marsh elevations; mid/high marsh elevations were found only in former uplands. At the highest century sea-levelrise and lowest sediment concentrations, the island marshes became dominated by mudflat elevations. Under the same sediment concentrations, low salinity brackish marshes containing highly productive vegetation had slower elevation loss compared to more saline sites with lower productivity. A similar trend was documented when comparing against a marsh accretion model that did not model vegetation feedbacks. Elevation predictions using the Marsh Equilibrium Model highlight the importance of including vegetation responses to sea-level

The evolution of tidal basins and estuaries in tropical and subtropical regions is often influenced by the presence of mangrove forests. These forests are amongst the most productive environments in the world and provide important ecosystem services. However, these intertidal habitats are also extremely vulnerable and are threatened by climate change impacts such as sealevelrise. It is therefore of key importance to improve our understanding of how tidal systems occupied by mangrove vegetation respond to rising water levels. An ecomorphodynamic model was developed that simulates morphological change and mangrove forest evolution as a result of mutual feedbacks between physical and biological processes. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. Under stable water levels, model results indicate that mangrove trees enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The landward expansion of the channels, on the other hand, is reduced. Model simulations including sealevelrise suggest that mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone. While the sealevel is rising, mangroves are migrating landward and the channel network tends to expand landward too. The presence of mangrove trees, however, was found to hinder both the branching and headward erosion of the landward expanding channels. Simulations are performed according to different sealevelrise scenarios and with different tidal range conditions to assess which tidal environments are most vulnerable. Changes in the properties of the tidal channel networks are being examined as well. Overall, model results highlight the role of mangroves in driving the

The rate of sealevel change relative to the land along the West Coast of the U.S. varies over a range of +5 to -2 mm/yr, as observed across the set of long-running tide gauges. We analyze tide gauge data in a network approach that accounts for temporal and spatial correlations in the time series of water levels observed at the stations. This analysis yields a set of rate estimates and realistic uncertainties that are minimally affected by varying durations of observations. The analysis has the greatest impact for tide gauges with short records, as the adjusted rate uncertainties for 2 to 3 decade duration tide gauges approach those estimated from unadjusted century-scale time series. We explore the sources of the wide range of observed relative sealevel rates through comparison with: 1) estimated vertical deformation rates derived from repeated leveling and GPS, 2) relative sealevel change predicted from models of glacial isostatic adjustment, and 3) geocentric sealevel rates estimated from satellite altimetry and century-scale reconstructions. Tectonic deformation is the dominant signal in the relative sealevel rates along the Cascadia portion of the coast, and is consistent with along-strike variation in locking behavior on the plate interface. Rates of vertical motion are lower along the transform portion of the plate boundary and include anthropogenic effects, but there are significant tectonic signals, particularly in the western Transverse Ranges of California where the crust is shortening across reverse faults. Preliminary analysis of different strategies of estimating the magnitude of geocentric sealevelrise suggest significant discrepancies between approaches. We will examine the implications of these discrepancies for understanding the process of regional geocentric sealevelrise in the northeastern Pacific Ocean, and associated projected impacts.

Approximately half of the world's population or 3.2 billion people lives within 200 km of coastlines and many of them in the world's deltaic plains. Sea-levelrise, widely recognized as one of consequences resulting from anthropogenic climate change, has induced substantial coastal vulnerability globally and in particular, in the deltaic regions, such as coastal Bangladesh, and Yangtze Delta. Bangladesh, a low-lying, one of the most densely populated countries in the world located at the Bay of Bengal, is prone to transboundary monsoonal flooding, potentially aggravated by more frequent and intensified cyclones resulting from anthropogenic climate change. Sea-levelrise, along with tectonic, sediment load and groundwater extraction induced land uplift/subsidence, have exacerbated Bangladesh's coastal vulnerability. Here we describe the physical science component of the integrated approach based on both physical and social sciences to address the adaption and potential mitigation of coastal Bangladesh vulnerability. The objective is to quantify the estimates of spatial varying sea-level trend separating the vertical motion of the coastal regions using geodetic and remote-sensing measurements (tide gauges, 1950-current; satellite altimetry, 1992-present, GRACE, 2003-present, Landsat/MODIS), reconstructed sea-level trends (1950-current), and GPS and InSAR observed land subsidence. Our goal is to conduct physically based robust projection of relative sea-level change at the end of the 21st century for the Bangladesh Delta to enable quantitative measures of social science based adaption and possible mitigation.

In this paper, we apply a new analytic tool to identify geographic areas in the contiguous United States that may be more likely to experience disproportionate impacts of sealevelrise (SLR), and to determine if and where socially vulnerable populations would bear disproportiona...

Island conservation programs have been spectacularly successful over the past five decades, yet they generally do not account for impacts of climate change. Here, we argue that the full spectrum of climate change, especially sea-levelrise and loss of suitable climatic conditions, should be rapidly integrated into island biodiversity research and management.

A four month experiment using greenhouse mesocosms was conducted to analyze the effects of eutrophication, sealevelrise, and precipitation changes on the salt marsh plant Spartina alterniflora. Pots containing plants were placed in six 600L tanks that received seawater pumped f...

Sealevelrise, precipitation, and eutrophication (3 X 3 X 2 factorial design) were simulated in tidal mesocosms in the US EPA Narragansett greenhouse. Each precipitation treatment (storm, drought, ambient rain) was represented in one of two tanks (control, fertilized). The contr...

During the 21st century, sea-levelrise is projected to have a wide range of effects on coastal environments, development, and infrastructure. Consequently, there has been an increased focus on developing modeling or other analytical approaches to evaluate potential impacts to inform coastal management. This report provides the data that were used to develop and evaluate the performance of a Bayesian network designed to predict long-term shoreline change due to sea-levelrise. The data include local rates of relative sea-levelrise, wave height, tide range, geomorphic classification, coastal slope, and shoreline-change rate compiled as part of the U.S. Geological Survey Coastal Vulnerability Index for the U.S. Atlantic coast. In this project, the Bayesian network is used to define relationships among driving forces, geologic constraints, and coastal responses. Using this information, the Bayesian network is used to make probabilistic predictions of shoreline change in response to different future sea-level-rise scenarios.

This article presents a commentary on the possibility of a global sea-levelrise because of shrinkage of the west antarctic ice sheet (WAIS). The WAIS is the focus of attention because of general agreement among glaciologists that only a marine ice sheet is likely to undergo rapid change, and WAIS appears to be the most vulnerable. 14 refs., 1 fig.

Future sealevelrise as a consequence of global warming will affect the world's coastal regions. Even though the pace of sealevelrise is not clear, the consequences will be severe and global. Commonly the effects of future sealevelrise are investigated for relatively vulnerable development countries; however, a whole range of varying regions needs to be considered in order to improve the understanding of global consequences. In this paper we investigate consequences of future sealevelrise along the coast of the Baltic Sea island of Gotland, Sweden, with the aim to fill knowledge gaps regarding comparatively well-suited areas in developed countries. We study both the quantity of the loss of features of infrastructure, cultural, and natural value in the case of a 2 m sealevelrise of the Baltic Sea and the effects of climate change on seawater intrusion in coastal aquifers, which indirectly cause saltwater intrusion in wells. We conduct a multi-criteria risk analysis by using lidar data on land elevation and GIS-vulnerability mapping, which gives the application of distance and elevation parameters formerly unimaginable precision. We find that in case of a 2 m sealevelrise, 3 % of the land area of Gotland, corresponding to 99 km2, will be inundated. The features most strongly affected are items of touristic or nature value, including camping places, shore meadows, sea stack areas, and endangered plants and species habitats. In total, 231 out of 7354 wells will be directly inundated, and the number of wells in the high-risk zone for saltwater intrusion in wells will increase considerably. Some valuable features will be irreversibly lost due to, for example, inundation of sea stacks and the passing of tipping points for seawater intrusion into coastal aquifers; others might simply be moved further inland, but this requires considerable economic means and prioritization. With nature tourism being one of the main income sources of Gotland, monitoring and

Evidence is presented from three estuarine tide gauges located in the Sundarban area of southwest Bangladesh of relative sealevelrise substantially in excess of the generally accepted rates from altimetry, as well as previous tide-gauge analyses. It is proposed that the difference arises from the use of Relative Mean SeaLevel (RMSL) to characterise the present and future coastal flood hazard, since RMSL can be misleading in estuaries in which tidal range is changing. Three tide gauges, one located in the uninhabited mangrove forested area (Sundarban) of southwest Bangladesh, the others in the densely populated polder zone north of the present Sundarban, show rates of increase in RMSL ranging from 2.8 mm a- 1 to 8.8 mm a- 1. However, these trends in RMSL disguise the fact that high water levels in the polder zone have been increasing at an average rate of 15.9 mm a- 1 and a maximum of 17.2 mm a- 1. In an area experiencing tidal range amplification, RMSL will always underestimate the rise in high water levels; consequently, as an alternative to RMSL, the use of trends in high water maxima or ‘Effective SeaLevel Rise’ (ESLR) is adopted as a more strategic parameter to characterise the flooding hazard potential. The rate of increase in ESLR is shown to be due to a combination of deltaic subsidence, including sediment compaction, and eustatic sealevelrise, but principally as a result of increased tidal range in estuary channels recently constricted by embankments. These increases in ESLR have been partially offset by decreases in fresh water discharge in those estuaries connected to the Ganges. The recognition of increases of the effective sealevel in the Bangladesh Sundarban, which are substantially greater than increases in mean sealevel, is of the utmost importance to flood management in this low-lying and densely populated area.

Aim The long-term stability of coastal ecosystems such as mangroves and salt marshes depends upon the maintenance of soil elevations within the intertidal habitat as sealevel changes. We examined the rates and processes of peat formation by mangroves of the Caribbean Region to better understand biological controls on habitat stability. Location Mangrove-dominated islands on the Caribbean coasts of Belize, Honduras and Panama were selected as study sites. Methods Biological processes controlling mangrove peat formation were manipulated (in Belize) by the addition of nutrients (nitrogen or phosphorus) to Rhizophora mangle (red mangrove), and the effects on the dynamics of soil elevation were determined over a 3-year period using rod surface elevation tables (RSET) and marker horizons. Peat composition and geological accretion rates were determined at all sites using radiocarbon-dated cores. Results The addition of nutrients to mangroves caused significant changes in rates of mangrove root accumulation, which influenced both the rate and direction of change in elevation. Areas with low root input lost elevation and those with high rates gained elevation. These findings were consistent with peat analyses at multiple Caribbean sites showing that deposits (up to 10 m in depth) were composed primarily of mangrove root matter. Comparison of radiocarbon-dated cores at the study sites with a sea-level curve for the western Atlantic indicated a tight coupling between peat building in Caribbean mangroves and sea-levelrise over the Holocene. Main conclusions Mangroves common to the Caribbean region have adjusted to changing sealevel mainly through subsurface accumulation of refractory mangrove roots. Without root and other organic inputs, submergence of these tidal forests is inevitable due to peat decomposition, physical compaction and eustatic sea-levelrise. These findings have relevance for predicting the effects of sea-levelrise and biophysical processes on tropical

The effects of sea-levelrise on the depth to the fresh water/salt water interface were simulated by using a density-dependent, three-dimensional numerical ground water flow model for a simplified hypothetical fresh water lens that is similar to shallow, coastal aquifers found along the Atlantic coast of the United States. Simulations of sea-levelrise of 2.65 mm/year from 1929 to 2050 resulted in an increase in water levels relative to a fixed datum, yet a net decrease in water levels relative to the increased sea-level position. The net decrease in water levels was much greater near a gaining stream than farther from the stream. The difference in the change in water levels is attributed to the dampening effect of the stream on water level changes in response to sea-levelrise. In response to the decreased water level altitudes relative to local sealevel, the depth to the fresh water/salt water interface decreased. This reduction in the thickness of the fresh water lens varied throughout the aquifer and was greatly affected by proximity to a ground water fed stream and whether the stream was tidally influenced. Away from the stream, the thickness of the fresh water lens decreased by about 2% from 1929 to 2050, whereas the fresh water lens thickness decreased by about 22% to 31% for the same period near the stream, depending on whether the stream was tidally influenced. The difference in the change in the fresh water/salt water interface position is controlled by the difference in the net decline in water levels relative to local sealevel. ?? 2007 National Ground Water Association.

NOAA is involved in a myriad of climate related research and projects that help decision makers and the public understand climate science as well as climate change impacts. The NOAA Office for Coastal Management (OCM) provides data, tools, trainings and technical assistance to coastal resource managers. Beginning in 2011, NOAA OCM began developing a sealevelrise and coastal flooding impacts viewer which provides nationally consistent data sets and analyses to help communities with coastal management goals such as: understanding and communicating coastal flood hazards, performing vulnerability assessments and increasing coastal resilience, and prioritizing actions for different inundation/flooding scenarios. The Viewer is available on NOAA's Digital Coast platform: (coast.noaa.gov/ditgitalcoast/tools/slr). In this presentation we will share the lessons learned from our work with coastal decision-makers on the role of coastal flood risk data and tools in helping to shape future land use decisions and policies. We will also focus on a recent effort in California to help users understand the similarities and differences of a growing array of sealevelrise decision support tools. NOAA staff and other partners convened a workshop entitled, "Lifting the Fog: Bringing Clarity to SeaLevelRise and Shoreline Change Models and Tools," which was attended by tool develops, science translators and coastal managers with the goal to create a collaborative communication framework to help California coastal decision-makers navigate the range of available sealevelrise planning tools, and to inform tool developers of future planning needs. A sealevelrise tools comparison matrix will be demonstrated. This matrix was developed as part of this effort and has been expanded to many other states via a partnership with NOAA, Climate Central, and The Nature Conservancy.

Sea-levelrise is a major factor in wetland loss worldwide, and in much of Chesapeake Bay (USA) the rate of sea-levelrise is higher than the current global rate of 3.2 mm yr-1 due to regional subsidence. Marshes along estuarine salinity gradients differ in vegetation composition, productivity, decomposition pathways, and sediment dynamics, and may exhibit different responses to sea-levelrise. Coastal marshes persist by building vertically at rates at or exceeding regional sea-levelrise. In one of the first studies to examine elevation dynamics across an estuarine salinity gradient, we installed 15 surface elevation tables (SET) and accretion marker-horizon plots (MH) in tidal freshwater, oligohaline, and brackish marshes across a Chesapeake Bay subestuary. Over the course of four years, wetlands across the subestuary decreased 1.8 ± 2.7 mm yr-1 in elevation on average, at least 5 mm yr-1 below that needed to keep pace with global sea-levelrise. Elevation change rates did not significantly differ among the marshes studied, and ranged from -9.8 ± 6.9 to 4.5 ± 4.3 mm yr-1. Surface accretion of deposited mineral and organic matter was uniformly high across the estuary (~9–15 mm yr-1), indicating that elevation loss was not due to lack of accretionary input. Position in the estuary and associated salinity regime were not related to elevation change or surface matter accretion. Previous studies have focused on surface elevation change in marshes of uniform salinity (e.g., salt marshes); however, our findings highlight the need for elevation studies in marshes of all salinity regimes and different geomorphic positions, and warn that brackish, oligohaline, and freshwater tidal wetlands may be at similarly high risk of submergence in some estuaries. PMID:27467784

Sea-levelrise is a major factor in wetland loss worldwide, and in much of Chesapeake Bay (USA) the rate of sea-levelrise is higher than the current global rate of 3.2 mm yr-1 due to regional subsidence. Marshes along estuarine salinity gradients differ in vegetation composition, productivity, decomposition pathways, and sediment dynamics, and may exhibit different responses to sea-levelrise. Coastal marshes persist by building vertically at rates at or exceeding regional sea-levelrise. In one of the first studies to examine elevation dynamics across an estuarine salinity gradient, we installed 15 surface elevation tables (SET) and accretion marker-horizon plots (MH) in tidal freshwater, oligohaline, and brackish marshes across a Chesapeake Bay subestuary. Over the course of four years, wetlands across the subestuary decreased 1.8 ± 2.7 mm yr-1 in elevation on average, at least 5 mm yr-1 below that needed to keep pace with global sea-levelrise. Elevation change rates did not significantly differ among the marshes studied, and ranged from -9.8 ± 6.9 to 4.5 ± 4.3 mm yr-1. Surface accretion of deposited mineral and organic matter was uniformly high across the estuary (~9-15 mm yr-1), indicating that elevation loss was not due to lack of accretionary input. Position in the estuary and associated salinity regime were not related to elevation change or surface matter accretion. Previous studies have focused on surface elevation change in marshes of uniform salinity (e.g., salt marshes); however, our findings highlight the need for elevation studies in marshes of all salinity regimes and different geomorphic positions, and warn that brackish, oligohaline, and freshwater tidal wetlands may be at similarly high risk of submergence in some estuaries.

Sea-levelrise will result in changes in water depth over coral reefs, which will influence reef platform growth as a result of carbonate production and accretion. This study simulates the pattern of reef response on the reefs around Lizard Island in the northern Great Barrier Reef. Two sea-levelrise scenarios are considered to capture the range of likely projections: 0.5 m and 1.2 m above 1990 levels by 2100. Reef topography has been established through extensive bathymetric profiling, together with available data, including LiDAR, single beam bathymetry, multibeam swath bathymetry, LADS and digitised chart data. The reef benthic cover around Lizard Island has been classified using a high resolution WorldView-2 satellite image, which is calibrated and validated against a ground referencing dataset of 364 underwater video records of the reef benthic character. Accretion rates are parameterised using published hydrochemical measurements taken in-situ and rules are applied using Boolean logic to incorporate geomorphological transitions associated with different depth ranges, such as recolonisation of the reef flat when it becomes inundated as sealevelrises. Simulations indicate a variable platform response to the different sea-levelrise scenarios. For the 0.5 m rise, the shallower reef flats are gradually colonised by corals, enabling this active geomorphological zone to keep up with the lower rate of rise while the other sand dominated areas get progressively deeper. In the 1.2 m scenario, a similar pattern is evident for the first 30 years of rise, beyond which the whole reef platform begins to slowly drown. To provide insight on reef response to sea-levelrise in other areas, simulation results of four different reef settings are discussed and compared at the southeast reef flat (barrier reef), Coconut Beach (fringing reef), Watson's Bay (leeward bay with coral patches) and Mangrove Beach (sheltered lagoonal embayment). The reef sites appear to accrete upwards

As part of a broad assessment of climate change impacts in Morocco, an assessment of vulnerability and adaptation of coastal zones to sea-levelrise was conducted. Tangier Bay which is the most important socio-economic pole in Northern Morocco represents one of the cases studies. Using a GIS-based inundation analysis and an erosion modelling approach, the potential physical vulnerability to acceleratedsea-levelrise was investigated, and the most vulnerable socio-economic sectors were assessed. Results indicate that 10% and 24% of the area will be at risk of flooding respectively for minimum (4 m) and maximum (11 m) inundation levels. The most severely impacted sectors are expected to be the coastal defences and the port, the urban area, tourist coastal infrastructures, the railway, and the industrial area. Shoreline erosion would affect nearly 20% and 45% of the total beach areas respectively in 2050 and 2100. Potential response strategies and adaptation options identified include: sand dune fixation, beach nourishment and building of seawalls to protect the urban and industrial areas of high value. It was also recommended that an Integrated Coastal Zone Management Plan for the region, including upgrading awareness, building regulation and urban growth planning should be the most appropriate tool to ensure a long-term sustainable development, while addressing the vulnerability of the coast to future sea-levelrise.

Land subsidence due to decline in head in confined aquifers, related to municipal and industrial water pumpage, is widespread in the Atlantic Coastal Plain. Although not a major engineering problem, subsidence greatly complicates adjustment of precise leveling and distorts prediction of future sea-levelrise. When preconsolidation stress equivalent to about 20 m of head decline is exceeded compaction of fine-grained sediments of the aquifer system begins, and continuous until a new head equilibrium is attained between fine and coarse units. The ratio subsidence/head decline is quite consistent, ranging form 0.0064 in southeastern Virginia to 0.0018 at Dover, Delaware and Atlantic City, New Jersey. Higher values are related to the occurrence of montmorillonite as the predominant clay mineral present. Review of tide gauge records indicates that gauges not affected by land subsidence or other local secular effects have been sinking relative to sealevel since 1940 at rates averaging about 2.5 mm/yr. of which 0.6 mm/yr is ascribed to glacio-isostatic adjustment to unloading of North America resulting from melting of late Pleistocene glaciers, and about 0.9 mm/yr is ascribed to steric sea-levelrise related to ocean warming. The residual 1 mm/yr of relative sea-levelrise is not well understood, but may be related to regional tectonic subsidence of the Atlantic coast.

An 8500-year Holocene simulation developed in GEOMBEST provides a possible scenario to explain the evolution of barrier coast between Rodanthe and Cape Hatteras, NC. Sensitivity analyses suggest that in the Outer Banks, the rate of sea-levelrise is the most important factor in determining how barrier islands evolve. The Holocene simulation provides a basis for future simulations, which suggest that if sealevelrises up to 0.88 m by AD 2100, as predicted by the highest estimates of the Intergovernmental Panel on Climate Change, the barrier in the study area may migrate on the order of 2.5 times more rapidly than at present. If sealevelrises beyond IPCC predictions to reach 1.4–1.9 m above modern sealevel by AD 2100, model results suggest that barrier islands in the Outer Banks may become vulnerable to threshold collapse, disintegrating during storm events, by the end of the next century. Consistent with sensitivity analyses, additional simulations indicate that anthropogenic activities, such as increasing the rate of sediment supply through beach nourishment, will only slightly affect barrier island migration rates and barrier island vulnerability to collapse.

Even if greenhouse gas emissions were stopped today, sealevel would continue to rise for centuries, with the long-term sea-level commitment of a 2 °C warmer world significantly exceeding 2 m. In view of the potential implications for coastal populations and ecosystems worldwide, we investigate, from an ice-dynamic perspective, the possibility of delaying sea-levelrise by pumping ocean water onto the surface of the Antarctic ice sheet. We find that due to wave propagation ice is discharged much faster back into the ocean than would be expected from a pure advection with surface velocities. The delay time depends strongly on the distance from the coastline at which the additional mass is placed and less strongly on the rate of sea-levelrise that is mitigated. A millennium-scale storage of at least 80 % of the additional ice requires placing it at a distance of at least 700 km from the coastline. The pumping energy required to elevate the potential energy of ocean water to mitigate the currently observed 3 mm yr-1 will exceed 7 % of the current global primary energy supply. At the same time, the approach offers a comprehensive protection for entire coastlines particularly including regions that cannot be protected by dikes.

Even if greenhouse gas emissions were stopped today sealevel would continue to rise for centuries with the long-term sea-level commitment of a two-degree-warmer world significantly exceeding 2 m. In view of the potential implications for coastal populations and ecosystems worldwide we investigate, from an ice-dynamic perspective, the possibility to delay sea-levelrise by pumping ocean water onto the surface of the Antarctic Ice Sheet. We find that due to wave propagation ice is discharged much faster back into the ocean than would be expected from a pure advection with surface velocities. The delay time depends strongly on the distance from the coastline at which the additional mass is placed and less strongly on the rate of sea-levelrise that is mitigated. A millennium-scale storage of at least 80 % of the additional ice requires placing it at a distance of at least 700 km from the coast line. The pumping energy required to elevate the potential energy of ocean water to mitigate the currently observed 3 mm yr-1 will exceed 7 % of the current global primary energy supply. At the same time the approach may be the only way to protect entire coastlines or specific regions that cannot be protected by dikes.

Iceberg calving and increased ice discharge from ice-shelf tributary glaciers contribute significant amounts to global sea-levelrise (SLR) from the Antarctic Peninsula (AP). Owing to ongoing ice dynamical changes (collapse of buttressing ice shelves), these contributions have accelerated in recent years. As the AP is one of the fastest warming regions on Earth, further ice dynamical adjustment (increased ice discharge) is expected over the next two centuries. In this paper, the first regional SLR projection of the AP from both iceberg calving and increased ice discharge from ice-shelf tributary glaciers in response to ice-shelf collapse is presented. An ice-sheet model forced by temperature output from 13 global climate models (GCMs), in response to the high greenhouse gas emission scenario (RCP8.5), projects AP contribution to SLR of 28 ± 16 to 32 ± 16 mm by 2300, partitioned approximately equally between contributions from tidewater glaciers and ice-shelf tributary glaciers. In the RCP4.5 scenario, sea-levelrise projections to 2300 are dominated by tidewater glaciers (∼8-18 mm). In this cooler scenario, 2.4 ± 1 mm is added to global sealevels from ice-shelf tributary drainage basins as fewer ice-shelves are projected to collapse. Sea-level projections from ice-shelf tributary glaciers are dominated by drainage basins feeding George VI Ice Shelf, accounting for ∼70% of simulated SLR. Combined total ice dynamical SLR projections to 2300 from the AP vary between 11 ± 2 and 32 ± 16 mm sea-level equivalent (SLE), depending on the emission scenario used. These simulations suggest that omission of tidewater glaciers could lead to a substantial underestimation of the ice-sheet's contribution to regional SLR.

rise and has the potential to sequester carbon. Saltmarsh exhibited a similar potential for carbon sequestration, but low resilience to risingsealevel, particularly in areas with steep or urbanised landward topography. Incorporation of these findings into general models of wetland hydrodynamics will inform strategies for adaptive management of estuarine wetlands in response to future climate change.

The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6-8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz-Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sealevelrise during this event. Sealevel rose ~14 m between 9.5 to 7.5 ka, a pattern consistent with coral records and the ICE-5G glacio-isostatic adjustment model. There were two distinct periods at ~8.9-8.8 and ~8.2-7.6 ka when Chesapeake marshes were drown as sealevel rose rapidly at least ~12 mm yr-1. The latter event occurred after the 8.6-8.2 ka cooling event, coincided with extreme warming and vigorous AMOC centered on 7.9 ka, and may have been due to Antarctic Ice Sheet decay.

Coastal stakeholders need defensible predictions of 21st century sea-levelrise (SLR). IPCC assessments suggest 21st century SLR of {approx}0.5 m under aggressive emission scenarios. Semi-empirical models project SLR of {approx}1 m or more by 2100. Although some sea-level contributions are fairly well constrained by models, others are highly uncertain. Recent studies suggest a potential large contribution ({approx}0.5 m/century) from the marine-based West Antarctic Ice Sheet, linked to changes in Southern Ocean wind stress. To assess the likelihood of fast retreat of marine ice sheets, we need coupled ice-sheet/ocean models that do not yet exist (but are well under way). CESM is uniquely positioned to provide integrated, physics based sea-level predictions.

The Yangtze Delta in China is vital economic hubs in terms of settlement, industry, agriculture, trade and tourism as well as of great environmental significance. In recent decades, the prospect of climate change, in particular sealevelrise and its effects on low lying coastal areas have generated worldwide attention to coastal ecosystems. Coastal wetlands, as important parts of coastal ecosystem, are particularly sensitive to sealevelrise. To study the responses of coastal wetlands to climate change, assess the impacts of climate change on coastal wetlands and formulate feasible and practical mitigation strategies are the important prerequisites for securing the coastal zone ecosystems. In this study, taking the coastal wetlands in the Yangtze Estuary as a case study, the potential impacts of sea-levelrise to coastal wetlands habitat were analyzed by the Source-Pathway-Receptor-Consequence (SPRC) model. The key indicators, such as the sea-levelrise rate, subsidence rate, elevation, daily inundation duration of habitat and sedimentation rate, were selected to build a vulnerability assessment system according to the IPCC definition of vulnerability, i.e. the aspects of exposure, sensitivity and adaptation. A quantitatively spatial assessment method on the GIS platform was established by quantifying each indicator, calculating the vulnerability index and grading the vulnerability. The vulnerability assessment on the coastal wetlands in the Yangtze Estuary under the sealevelrise rate of the present trend and IPCC A1F1 scenario were performed for three sets of projections of short-term (2030s), mid-term (2050s) and long-term (2100s). The results showed that at the present trend of sealevelrise rate of 0.26 cm/a, 92.3 % of the coastal wetlands in the Yangtze Estuary was in the EVI score of 0 in 2030s, i.e. the impact of sealevelrise on habitats/species of coastal wetlands was negligible. While 7.4 % and 0.3 % of the coastal wetlands were in the EVI score of

Coastal regions become unprecedentedly vulnerable to coastal hazards that are associated with sealevelrise. The purpose of this paper is therefore to simulate prospective urban exposure to changing sealevels. This article first applied the cellular-automaton-based SLEUTH model (Project Gigalopolis, 2016) to calibrate historical urban dynamics in Bay County, Florida (USA) - a region that is greatly threatened by risingsealevels. This paper estimated five urban growth parameters by multiple-calibration procedures that used different Monte Carlo iterations to account for modeling uncertainties. It then employed the calibrated model to predict three scenarios of urban growth up to 2080 - historical trend, urban sprawl, and compact development. We also assessed land use impacts of four policies: no regulations; flood mitigation plans based on the whole study region and on those areas that are prone to experience growth; and the protection of conservational lands. This study lastly overlaid projected urban areas in 2030 and 2080 with 500-year flooding maps that were developed under 0, 0.2, and 0.9 m sealevelrise. The calibration results that a substantial number of built-up regions extend from established coastal settlements. The predictions suggest that total flooded area of new urbanized regions in 2080 would be more than 25 times that under the flood mitigation policy, if the urbanization progresses with few policy interventions. The joint model generates new knowledge in the domain between land use modeling and sealevelrise. It contributes to coastal spatial planning by helping develop hazard mitigation schemes and can be employed in other international communities that face combined pressure of urban growth and climate change.

This study presents a method to assess the contributions of 21st-century sea-levelrise and groundwater extraction to sea water intrusion in coastal aquifers. Sea water intrusion is represented by the landward advance of the 10,000 mg/L iso-salinity line, a concentration of dissolved salts that renders groundwater unsuitable for human use. A mathematical formulation of the resolution of sea water intrusion among its causes was quantified via numerical simulation under scenarios of change in groundwater extraction and sea-levelrise in the 21st century. The developed method is illustrated with simulations of sea water intrusion in the Seaside Area sub-basin near the City of Monterey, California (USA), where predictions of mean sea-levelrise through the early 21st century range from 0.10 to 0.90 m due to increasing global mean surface temperature. The modeling simulation was carried out with a state-of-the-art numerical model that accounts for the effects of salinity on groundwater density and can approximate hydrostratigraphic geometry closely. Simulations of sea water intrusion corresponding to various combinations of groundwater extraction and sea-levelrise established that groundwater extraction is the predominant driver of sea water intrusion in the study aquifer. The method presented in this work is applicable to coastal aquifers under a variety of other scenarios of change not considered in this work. For example, one could resolve what changes in groundwater extraction and/or sealevel would cause specified levels of groundwater salinization at strategic locations and times.

Sealevel changes are typically caused by several natural phenomena, including ocean thermal expansion, glacial melt from Greenland and Antarctica. Global average sealevel is expected to rise, through the twenty-first century, according to the IPCC projections by between 0.18 and 0.59 cm. Such a rise in sealevel will significantly impact coastal area of the Nile Delta, consisting generally of lowland and is densely populated areas and accommodates significant proportion of Egypt's economic activities and built-up areas. The Nile Delta has been examined in several previous studies, which worked under various hypothetical sealevelrise (SLR) scenarios and provided different estimates of areas susceptible to inundation due to SLR. The paper intends, in this respect, to identify areas, as well as land use/land cover, susceptible to inundation by SLR based upon most recent scenarios of SLR, by the year 2100 using GIS. The results indicate that about 22.49, 42.18, and 49.22 % of the total area of coastal governorates of the Nile Delta would be susceptible to inundation under different scenarios of SLR. Also, it was found that 15.56 % of the total areas of the Nile Delta that would be vulnerable to inundation due to land subsidence only, even in the absence of any rise in sealevel. Moreover, it was found that a considerable proportion of these areas (ranging between 32.32 and 53.66 %) are currently either wetland or undeveloped areas. Furthermore, natural and/or man-made structures, such as the banks of the International Coastal Highway, were found to provide unintended protection to some of these areas. This suggests that the inundation impact of SLR on the Nile Delta is less than previously reported.

Subterranean estuary occupies the transition zone between hypoxic fresh groundwater and oxic seawater, and between terrestrial and marine sediment deposits. Consequently, we hypothesize, in a subterranean estuary, biogeochemical reactions of Fe respond to submarine groundwater discharge (SGD) and sealevelrise. Porewater and sediment samples were collected across a 30-m wide freshwater discharge zone of the Indian River Lagoon (Florida, USA) subterranean estuary, and at a site 250. m offshore. Porewater Fe concentrations range from 0.5 ??M at the shoreline and 250. m offshore to about 286 ??M at the freshwater-saltwater boundary. Sediment sulfur and porewater sulfide maxima occur in near-surface OC-rich black sediments of marine origin, and dissolved Fe maxima occur in underlying OC-poor orange sediments of terrestrial origin. Freshwater SGD flow rates decrease offshore from around 1 to 0.1. cm/day, while bioirrigation exchange deepens with distance from about 10. cm at the shoreline to about 40. cm at the freshwater-saltwater boundary. DOC concentrations increase from around 75 ??M at the shoreline to as much as 700 ??M at the freshwater-saltwater boundary as a result of labile marine carbon inputs from marine SGD. This labile DOC reduces Fe-oxides, which in conjunction with slow discharge of SGD at the boundary, allows dissolved Fe to accumulate. Upward advection of fresh SGD carries dissolved Fe from the Fe-oxide reduction zone to the sulfate reduction zone, where dissolved Fe precipitates as Fe-sulfides. Saturation models of Fe-sulfides indicate some fractions of these Fe-sulfides get dissolved near the sediment-water interface, where bioirrigation exchanges oxic surface water. The estimated dissolved Fe flux is approximately 0.84 ??M Fe/day per meter of shoreline to lagoon surface waters. Acceleratedsealevelrise predictions are thus likely to increase the Fe flux to surface waters and local primary productivity, particularly along coastlines where

Estuaries are geologically transitory features whose evolution depends on a delicate balance among relative sealevel basin geometry, shoreline erosion, fluvial sediment discharge, littoral drift, and tidal exchange. Models of modern estuarine development require specific sealevel scenarios; almost all assume a continuation of the decelerating sealevelrise of the last few thousand years. However, under constant external conditions, estuaries are ephemeral because they rapidly fill with fluvial and marine sediment. The rate of filling changes with time, but only a few thousand years are required to fill most estuaries. The persistence of estuaries, therefore, requires that relative sealevelrises at a rate sufficient to compensate for the inherent tendency of estuaries to fill with sediment. Coastal plain estuaries, of which Chesapeake Bay is a prime example, are often referred to as drowned river valleys. Although this description is appropriate for the first-order morphology of Chesapeake Bay, the implied passivity can be misleading, especially in the high-tidal-energy area of the bay mouth where dramatic spit progradation and channel migration have occurred in the last few thousand years. Holocene sediment accumulation rates are more irregular along the length of the estuary than most models would predict; but in general, sediment accumulation has been greater at the mouth and at the head of the bay and less along the middle reaches. If relative sealevel were to stabilize, the estuary would fill with sediment from both ends within a few thousand years. Evidence for two previous generations of the bay is preserved as the estuarine fill of major fluvial valleys, demonstrating that estuarine episodes have been closely tied to cyclic sealevel changes.

The analysis of more than 90 tidal gauge records, 10,000-km high resolution seismic profiles, 500 vibracores, and 250 radiocarbon dates led to the development of a new sealevel history for the Louisiana coastal zone and adjacent continental shelf for the last 8,000 years. Now reinterpreted, the original single delta plain is seen as actually two individual, imbricated shelf-phase delta plains deposited at different sealevels. Termed the modern and late Holocene, these two delta plains are separated by a regional shoreface refinement surface, which can be traced updip to the relict-transgressive Teche shoreline. The Late Holocene delta plain was deposited during a sealevel stillstand 6 m below the present, 3,000-7,2000 years ago. A 5 to 6-m eustatic-enhanced relative rise in sealevel, 2,5000-3,000 years ago at a rate of 1-1.2 cm/yr led to the complete transgresive submergence of the lower late Holocene delta plain. Sealevel reached its approximate position about 2,500 years ago, and since then the Mississippi River has built the modern delta plain consisting of the abandoned St. Bernard and Lafourche delta complexes and the active Balize and Atchafalaya delta complexes.

Coastal flooding due to storm surge and high tides is a serious risk for inhabitants of the Ganges-Brahmaputra-Meghna (GBM) delta, as much of the land is close to sealevel. Climate change could lead to large areas of land being subject to increased flooding, salinization and ultimate abandonment in West Bengal, India, and Bangladesh. IPCC 5th assessment modelling of sealevelrise and estimates of subsidence rates from the EU IMPACT2C project suggest that sealevel in the GBM delta region may rise by 0.63 to 0.88 m by 2090, with some studies suggesting this could be up to 0.5 m higher if potential substantial melting of the West Antarctic ice sheet is included. These sealevelrise scenarios lead to increased frequency of high water coastal events. Any effect of climate change on the frequency and severity of storms can also have an effect on extreme sealevels. A shelf-sea model of the Bay of Bengal has been used to investigate how the combined effect of sealevelrise and changes in other environmental conditions under climate change may alter the frequency of extreme sealevel events for the period 1971 to 2099. The model was forced using atmospheric and oceanic boundary conditions derived from climate model projections and the future scenario increase in sealevel was applied at its ocean boundary. The model results show an increased likelihood of extreme sealevel events through the 21st century, with the frequency of events increasing greatly in the second half of the century: water levels that occurred at decadal time intervals under present-day model conditions occurred in most years by the middle of the 21st century and 3-15 times per year by 2100. The heights of the most extreme events tend to increase more in the first half of the century than the second. The modelled scenarios provide a case study of how sealevelrise and other effects of climate change may combine to produce a greatly increased threat to life and property in the GBM delta by the end

This paper presents an assessment of global sealevelrise and the need to incorporate projections of rise into management plans for coastal adaptation. It also discusses the performance of a shoreline revetment; M. Ali Seawall, placed to protect the land against flooding and overtopping at coastal site, within Abu Qir Bay, East of Alexandria, Egypt along the Nile Delta coast. The assessment is conducted to examine the adequacy of the seawall under the current and progressive effects of climate change demonstrated by the anticipated sealevelrise during this century. The Intergovernmental Panel on Climate Change (IPCC, 2007) predicts that the Mediterranean will rise 30 cm to 1 meter this century. Coastal zone management of the bay coastline is of utmost significance to the protection of the low agricultural land and the industrial complex located in the rear side of the seawall. Moreover this joint research work highlights the similarity of the nature of current and anticipated coastal zone problems, at several locations around the world, and required adaptation and protection measures. For example many barrier islands in the world such as that in the Atlantic and Gulf of Mexico coasts of the U.S., lowland and deltas such as in Italy and the Nile Delta, and many islands are also experiencing significant levels of erosion and flooding that are exacerbated by sealevelrise. Global Climatic Changes: At a global scale, an example of the effects of accelerated climate changes was demonstrated. In recent years, the impacts of natural disasters are more and more severe on coastal lowland areas. With the threats of climate change, sealevelrise storm surge, progressive storm and hurricane activities and potential subsidence, the reduction of natural disasters in coastal lowland areas receives increased attention. Yet many of their inhabitants are becoming increasingly vulnerable to flooding, and conversions of land to open ocean. These global changes were recently

The purpose of this study was to explore the process of developing a learning progression (LP) on constructing explanations about sealevelrise. I used a learning progressions theoretical framework informed by the situated cognition learning theory. During this exploration, I explicitly described my decision-making process as I developed and revised a hypothetical learning progression. Correspondingly, my research question was: What is a process by which a hypothetical learning progression on sealevelrise is developed into an empirical learning progression using learners' explanations? To answer this question, I used a qualitative descriptive single case study with multiple embedded cases (Yin, 2014) that employed analytic induction (Denzin, 1970) to analyze data collected on middle school learners (grades 6-8). Data sources included written artifacts, classroom observations, and semi-structured interviews. Additionally, I kept a researcher journal to track my thinking about the learning progression throughout the research study. Using analytic induction to analyze collected data, I developed eight analytic concepts: participant explanation structures varied widely, global warming and ice melt cause sealevelrise, participants held alternative conceptions about sealevelrise, participants learned about thermal expansion as a fundamental aspect of sealevelrise, participants learned to incorporate authentic scientific data, participants' mental models of the ocean varied widely, sea ice melt contributes to sealevelrise, and participants held vague and alternative conceptions about how pollution impacts the ocean. I started with a hypothetical learning progression, gathered empirical data via various sources (especially semi-structured interviews), revised the hypothetical learning progression in response to those data, and ended with an empirical learning progression comprising six levels of learner thinking. As a result of developing an empirically based LP

Sea-levelrise (SLR) causes estimates of flood risk made under the assumption of stationary mean sealevel to be biased low. However, adjustments to flood return levels made assuming fixed increases of sealevel are also inaccurate when applied to sealevel that is rising over time at an uncertain rate. To accommodate both the temporal dynamics of SLR and their uncertainty, we develop an Average Annual Design Life Level (AADLL) metric and associated SLR allowances [1,2]. The AADLL is the flood level corresponding to a time-integrated annual expected probability of occurrence (AEP) under uncertainty over the lifetime of an asset; AADLL allowances are the adjustment from 2000 levels that maintain current risk. Given non-stationary and uncertain SLR, AADLL flood levels and allowances provide estimates of flood protection heights and offsets for different planning horizons and different levels of confidence in SLR projections in coastal areas. Allowances are a function primarily of local SLR and are nearly independent of AEP. Here we employ probabilistic SLR projections [3] to illustrate the calculation of AADLL flood levels and allowances with a representative set of long-duration tide gauges along U.S. coastlines. [1] Rootzen et al., 2014, Water Resources Research 49: 5964-5972. [2] Hunter, 2013, Ocean Engineering 71: 17-27. [3] Kopp et al., 2014, Earth's Future 2: 383-406.

Based on the sealevel budget closure approach, this study investigates the consistency of observed Global Mean SeaLevel (GMSL) estimates from satellite altimetry, observed Ocean Thermal Expansion (OTE) estimates from in-situ hydrographic data (based on Argo for depth above 2000m and oceanic cruises below) and GRACE observations of land water storage and land ice melt for the period January 2004 to December 2014. The consistency between these datasets is a key issue if we want to constrain missing contributions to sealevelrise such as the deep ocean contribution. Numerous previous studies have addressed this question by summing up the different contributions to sealevelrise and comparing it to satellite altimetry observations (see for example Llovel et al. 2015, Dieng et al. 2015). Here we propose a novel approach which consists in correcting GRACE solutions over the ocean (essentially corrections of stripes and leakage from ice caps) with mass observations deduced from the difference between satellite altimetry GMSL and in-situ hydrographic data OTE estimates. We check that the resulting GRACE corrected solutions are consistent with original GRACE estimates of the geoid spherical harmonic coefficients within error bars and we compare the resulting GRACE estimates of land water storage and land ice melt with independent results from the literature. This method provides a new mass redistribution from GRACE consistent with observations from Altimetry and OTE. We test the sensibility of this method to the deep ocean contribution and the GIA models and propose best estimates.

Rising mean sealevel, it is proposed, is a significant indicator of global climate change. The principal factors that can have contributed to the observed increases of global mean sealevel in recent decades are thermal expansion of the oceans and the discharge of polar ice sheets. Calculations indicate that thermal expansion cannot be the sole factor responsible for the observed rise in sealevel over the last 40 years; significant discharges of polar ice must also be occurring. Global warming, due in some degree presumably to increasing atmospheric carbon dioxide, has been opposed by the extraction of heat necessary to melt the discharged ice. During the past 40 years more than 50,000 cubic kilometers of ice has been discharged and has melted, reducing the surface warming that might otherwise have occurred by as much as a factor of 2. The transfer of mass from the polar regions to a thin spherical shell covering all the oceans should have increased the earth's moment of inertia and correspondingly reduced the speed of rotation by about 1.5 parts in 10(8). This accounts for about three quarters of the observed fractional reduction in the earth's angular velocity since 1940. Monitoring of global mean sealevel, ocean surface temperatures, and the earth's speed of rotation should be complemented by monitoring of the polar ice sheets, as is now possible by satellite altimetry. All parts of the puzzle need to be examined in order that a consistent picture emerge.

Secular sealevel trends extracted from tide gauge records of appropriately long duration demonstrate that global sealevel may be rising at a rate in excess of 1 millimeter per year. However, because global coverage of the oceans by the tide gauge network is highly nonuniform and the tide gauge data reveal considerable spatial variability, there has been a well-founded reluctance to interpret the observed secular sealevelrise as representing a signal of global scale that might be related to the greenhouse effect. When the tide gauge data are filtered so as to remove the contribution of ongoing glacial isostatic adjustement to the local sealevel trend at each location, then the individual tide gauge records reveal sharply reduced geographic scatter and suggest that there is a globally coherent signal of strength 2.4 {plus minus} 0.90 millimeters per year that is active in the system. This signal could constitute an indication of global climate warming. 15 refs., 8 figs.

We analyse the statistical relationship between changes in global temperature, global steric sealevel and radiative forcing in order to reveal causal relationships. There are in this, however, potential pitfalls due to the trending nature of the time series. We therefore apply a statistical method called cointegration analysis, originating from the field of econometrics, which is able to correctly handle the analysis of series with trends and other long-range dependencies. Further, we find a relationship between steric sealevel and temperature and find that temperature causally depends on the steric sealevel, which can be understood as a consequence of the large heat capacity of the ocean. This result is obtained both when analyzing observed data and data from a CMIP5 historical model run. Finally, we find that in the data from the historical run, the steric sealevel, in turn, is driven by the external forcing. Finally, we demonstrate that combining these two results can lead to a novel estimate of radiative forcing back in time based on observations.

Recent global models predict a rise of approximately one meter in global sealevel by 2100, with potentially larger increases in areas of the Pacific Ocean. If current climate change trends continue, low-lying islands across the globe may become inundated over the next century, placing island biodiversity at risk. Adding to the risk of inundation due to sealevelrise is the occurrence of cyclones and tsunamis. This combined trend will affect the low-lying islands of the Northwestern Hawaiian Islands and it is therefore important to assess its impact since these islands are critical habitats to many endangered endemic species and support the largest tropical seabird rookery in the world. The 11 March 2011 Tohoku (Mw=8.8) earthquake-tsunami affected the habitat of many endangered endemic species in Midway Atoll National Wildlife Refuge because all three islands (Sand, Eastern and Spit) were inundated by tsunami waves. At present sealevel, some tsunamis from certain source regions would not affect Midway Atoll. For example, the previous earthquake-tsunamis such as the 15 November 2006 Kuril (Mw=8.1) and 13 February 2007 Kuril (Mw=7.9) were not significant enough to affect Midway Atoll. But at higher sealevels, tsunamis with similar characteristics could pose a threat to such terrestrial habitats and wildlife. To visualize projected impacts to vegetation composition, wildlife habitat, and wildlife populations, we explored and analyzed inundation vulnerability for a range of possible sealevelrise and tsunami scenarios at Midway Atoll National Wildlife Refuge. Studying the combined threat of tsunamis and sealevelrise can provide more accurate and comprehensive assessments of the vulnerability of the unique natural resources on low-lying islands. A passive sealevelrise model was used to determine how much inundation will occur at different sealevelrise values for the three islands of Midway Atoll and each scenario was coupled with NOAA Center for Tsunami

Increasing rates of relative sea-levelrise (RSL) have been linked to coastal wetland losses along the Gulf of Mexico and elsewhere. Rapidly rising RSL may be affecting New England tidal marshes. Studies of the Wequetequock-Pawcatuck tidal marshes over four decades have documented dramatic changes in vegetation apparently related primarily to differential rates of marsh accretion and sea-levelrise though sediment supply and anthropogenic modifications of the system may also be involved. When initially studied in 1947-1948 the high marsh supported a Juncus gerardi-Spartina patens belting pattern typical of many New England salt marshes. On most of the marsh complex the former Juncus belt has now been replaced by forbs, primarily Triglochin maritima, while the former S. patens high marsh is now a complex of vegetation types-stunted Spartina alterniflora, Distichlis spicata, forbs, and relic stands of S. patens. The mean surface elevation of areas where the vegetation has changed is significantly lower than that of areas still supporting the earlier pattern (4.6 vs. 13.9 cm above mean tide level). The differences in surface elevation reflect differences in accretion of marsh peat. Stable areas have been accreting at the rate of local sea-levelrise, 2.0-2.5 mm/yr at least since 1938; changed areas have accreted at about one half that rate. Lower surface elevations result in greater frequency and duration of tidal flooding, and thus in increased peat saturation, salinity, and sulfide concentrations, and in decreased redox potential, as directly measured over the growing season at both changed and stable sites. These edaphic changes may have combined to favor establishment of a wetter, more open vegetation type. Similar changes have been observed on other Long Island Sound marshes and may be a model for the potential effects of sea-levelrise on New England tidal salt marshes. 39 refs., 4 figs., 1 tab.

Global sealevelrise in the past century due to climate change has been seen at an average rate of approximately 1.7-2.2 mm per year, with an increasing rate over the next century. The increasing SLR rate poses a severe threat to the low-lying land surface and the shallow groundwater system in the Kennedy Space Center in Florida, resulting in saltwater intrusion and groundwater induced flooding. A three-dimensional groundwater flow and salinity transport model is implemented to investigate and evaluate the extent of floods due to rising water table as well as saltwater intrusion. The SEAWAT model is chosen to solve the variable-density groundwater flow and salinity transport governing equations and simulate the regional-scale spatial and temporal evolution of groundwater level and chloride concentration. The horizontal resolution of the model is 50 m, and the vertical domain includes both the Surficial Aquifer and the Floridan Aquifer. The numerical model is calibrated based on the observed hydraulic head and chloride concentration. The potential impacts of sealevelrise on saltwater intrusion and groundwater induced flooding are assessed under various sealevelrise scenarios. Based on the simulation results, the potential landward movement of saltwater and freshwater fringe is projected. The existing water supply wells are examined overlaid with the projected salinity distribution map. The projected Surficial Aquifer water tables are overlaid with data of high resolution land surface elevation, land use and land cover, and infrastructure to assess the potential impacts of sealevelrise. This study provides useful tools for decision making on ecosystem management, water supply planning, and facility management.

The San Francisco South Bay Area in California is home to approximately seven million people that consist of nine counties and the prosperous core area of IT technology industry in the West Coast of America, well known as Silicon Valley. Sealevelrising due to Global Warming is becoming the main issue in this area. Furthermore, the extreme weather events including flash flooding are observing more frequently. Urban infrastructures are faced vulnerable at risk of long-term flooding. Sealevelrise by global warming in this area is estimated that it could rise by up to 16 inches (40 cm) by mid of this century and 55 inches (140 cm) by the end of this century. By the impact of 55 inches of sealevelrise, there could be 62 billion dollars loss and 270,000 people could be faced at risk of flooding. Nevertheless, urban areas are expecting to extend approximately 5,063.71 km2 by 2020 and 6,098.20 km2 by year 2050. Thus, the land use legislation need to be discussed following that the 213,000 acres that could be vulnerable to flooding by the end of this century. Adaptation strategies should be considered from various aspects including policy, empirical observations and academic approaches. In this paper, for promoting further discussions, vulnerable areas and its characteristics by flooding is assessed and the finding potential urban growth areas for urban rezoning is implemented using Geographic Information System.

The future of river deltas is believed to depend mainly on sealevelrise (SLR) and on the processes controlling the adaptation of the substrate to human impacts. The deltas are increasingly deprived of riverine sediment by river diversion, dams, dykes and the destruction of wetlands, and they are often sinking due to mining for groundwater, gas and petroleum. The relative sealevelrise is causing severe negative impacts in many river deltas worldwide. With continuously risingsealevels, this impact is expected to increase over time. The increased risk of delta flooding caused by tidal deformation associated with SLR in shallow coastal waters has received less attention. In this study, we demonstrate this effect for the case of the Mekong Delta where this study suggests that the maximum tidal water level and the tidal amplitude are increasing while the tidal phase at the coast is decreasing. In addition, the maximum water levels is rising faster than SLR because the tides themselves are modified by SLR. This effect is particularly pronounced for semi-diurnal tides and less so for diurnal tides. Similar effects may prevail for river deltas with extensive shallow coastal waters elsewhere in the world and deserve further investigation.

A number of researchers have reported on acceleratedsealevel along the east coast of North America, particularly in the northeast. We have previously modeled sea-level rates and accelerations from the last half of the 20th and early 21st centuries inferred from tide gauges in this region using steric sea-level changes, gravitationally self-consistent sea-level changes that includes self-attraction and loading (SAL), and glacial isostatic adjustment (GIA). We have found that, whereas the spatial variability of sea-level rates is dominated by GIA, the observed accelerations are not explained by these processes. In this talk, we first further investigate the observed accelerations, which we took to be constant during the study period. We have found, however, some evidence that the accelerations began in the timeframe 1990-2000. For example, the figure below shows the root-mean-square (rms) residual after removing a best-fit model wherein the acceleration was zero before the indicated year, for the Boston tide gauge, having one of the longest tide-gauge records. The minimimum rms residual occurs in the year 2000. A Monte Carlo simulation (red curve) shows that no time-dependence is expected from white noise. Evaluation of the statistical significance of these results has been difficult, since the postfit residuals are dominated by interannual variability. We will utilize time-dependent models for dynamic sea-level changes (including steric changes), GIA. For the Greenland ice mass, we will combine estimates of Greenland ice-mass variability obtained from recent analyses of GRACE data with long-term climate models for Greenland (from, e.g., RACMO) to calculate long-term sea-level impact. Comparing these models with tide-gauge data will yield insights into the nature and timing of acceleratedsealevel in this region. We will also discuss the implciations of these models for long-term global sea-level change.

Flood risk and sealevelrise impacts were assessed for the Port Authority of New York and New Jersey (PANYNJ) at four airports in the New York City area. These airports included John F. Kennedy International, LaGuardia, Newark International, and Teterboro Airports. Quantifying both present day and future flood risk due to climate change and developing flood mitigation alternatives is crucial for the continued operation of these airports. During Hurricane Sandy in October 2012 all four airports were forced to shut down, in part due to coastal flooding. Future climate change and sealevelrise effects may result in more frequent shutdowns and disruptions in travel to and from these busy airports. The study examined the effects of the 1%-annual-chance coastal flooding event for present day existing conditions and six different sealevelrise scenarios at each airport. Storm surge model outputs from the Federal Emergency Management Agency (FEMA) provided the present day storm surge conditions. 50th and 90thpercentile sealevelrise projections from the New York Panel on Climate Change (NPCC) 2013 report were incorporated into storm surge results using linear superposition methods. These projections were evaluated for future years 2025, 2035, and 2055. In addition to the linear superposition approach for storm surge at airports where waves are a potential hazard, one dimensional wave modeling was performed to get the total water level results. Flood hazard and flood depth maps were created based on these results. In addition to assessing overall flooding at each airport, major at-risk infrastructure critical to the continued operation of the airport was identified and a detailed flood vulnerability assessment was performed. This assessment quantified flood impacts in terms of potential critical infrastructure inundation and developed mitigation alternatives to adapt to coastal flooding and future sealevel changes. Results from this project are advancing the PANYNJ

Sea-levelrise, as a result of climate change, will likely inflict considerable economic consequences on coastal regions, particularly low-lying island states like Singapore. Although the literature has addressed the vulnerability of developed coastal lands, this is the first economic study to address nonmarket lands, such as beaches, marshes and mangrove estuaries. This travel cost and contingent valuation study reveals that consumers in Singapore attach considerable value to beaches. The contingent valuation study also attached high values to marshes and mangroves but this result was not supported by the travel cost study. Although protecting nonmarket land uses from sea-levelrise is expensive, the study shows that at least highly valued resources, such as Singapore's popular beaches, should be protected.

83 National Park Service (NPS) units contain nearly 12,000 miles of coastal, estuarine and Great Lakes shoreline and their associated resources. Iconic natural features exist along active shorelines in NPS units, including, e.g., Cape Cod, Padre Island, Hawaii Volcanoes, and the Everglades. Iconic cultural resources managed by NPS include the Cape Hatteras Lighthouse, Fort Sumter, the Golden Gate, and heiaus and fish traps along the coast of Hawaii. Impacts anticipated from sealevelrise include inundation and flooding of beaches and low lying marshes, shoreline erosion of coastal areas, and saltwater intrusion into the water table. These impacts and other coastal hazards will threaten park beaches, marshes, and other resources and values; alter the viability of coastal roads; and require the NPS to re-evaluate the financial, safety, and environmental implications of maintaining current projects and implementing future projects in ocean and coastal parks in the context of sealevelrise. Coastal erosion will increase as sealevelsrise. Barrier islands along the coast of Louisiana and North Carolina may have already passed the threshold for maintaining island integrity in any scenario of sealevelrise (U.S. Climate Change Science Program Synthesis and Assessment Program Report 4.1). Consequently, sealevelrise is expected to hasten the disappearance of historic coastal villages, coastal wetlands, forests, and beaches, and threaten coastal roads, homes, and businesses. While sealevel is rising in most coastal parks, some parks are experiencing lower water levels due to isostatic rebound and lower lake levels. NPS funded a Coastal Vulnerability Project to evaluate the physical and geologic factors affecting 25 coastal parks. The USGS Open File Reports for each park are available at http://woodshole.er.usgs.gov/project-pages/. These reports were designed to inform park planning efforts. NPS conducted a Storm Vulnerability Project to provide ocean and coastal

Glaciers distinct from the Greenland and Antarctic Ice Sheets are losing large amounts of water to the world's oceans. However, estimates of their contribution to sealevelrise disagree. We provide a consensus estimate by standardizing existing, and creating new, mass-budget estimates from satellite gravimetry and altimetry and from local glaciological records. In many regions, local measurements are more negative than satellite-based estimates. All regions lost mass during 2003-2009, with the largest losses from Arctic Canada, Alaska, coastal Greenland, the southern Andes, and high-mountain Asia, but there was little loss from glaciers in Antarctica. Over this period, the global mass budget was -259 ± 28 gigatons per year, equivalent to the combined loss from both ice sheets and accounting for 29 ± 13% of the observed sealevelrise.

Climate science and sealevel models constantly evolve. In this context, maps and analyses of exposure to sealevelrise - or coastal flooding aggravated by rise - quickly fall out of date when based upon a specific model projection or projection set. At the same time, policy makers and planners prefer simple and stable risk assessments for their future planning. Here, using Climate Central's Surging Seas Risk Finder, we describe and illustrate a decision tool framework that separates the spatial and temporal dimensions of coastal exposure in order to help alleviate this tension. The Risk Finder presents local maps and exposure analyses simply as functions of a discrete set of local water levels. In turn, each water level may be achieved at different times, with different probabilities, according to different combinations of sealevel change, storm surge and tide. This temporal dimension is expressed in a separate module of the Risk Finder, so that users may explore the probabilities and time frames of different water levels, as a function of different sealevel models and emissions scenarios. With such an approach, decision-makers can quickly get a sense of the range of risks for each water level given current understanding. At the same time, the models and scenarios can easily be updated over time as the science evolves, while avoiding the labor of regenerating maps and exposure analyses. In this talk, we will also use the tool to highlight key findings from a new U.S. national assessment of sealevel and coastal flood risk. For example, more than 2.5 million people and $500 billion dollars of property value sit on land less than 2 meters above the high tide line in Florida alone.

The contributions from terrestrial water sources to sea-levelrise, other than ice caps and glaciers, are highly uncertain and heavily debated. Recent assessments indicate that groundwater depletion (GWD) may become the most important positive terrestrial contribution over the next 50 years, probably equal in magnitude to the current contributions from glaciers and ice caps. However, the existing estimates assume that nearly 100% of groundwater extracted eventually ends up in the oceans. Owing to limited knowledge of the pathways and mechanisms governing the ultimate fate of pumped groundwater, the relative fraction of global GWD that contributes to sea-levelrise remains unknown. Here, using a coupled climate-hydrological model simulation, we show that only 80% of GWD ends up in the ocean. An increase in runoff to the ocean accounts for roughly two-thirds, whereas the remainder results from the enhanced net flux of precipitation minus evaporation over the ocean, due to increased atmospheric vapour transport from the land to the ocean. The contribution of GWD to global sea-levelrise amounted to 0.02 (+/-0.004) mm yr-1 in 1900 and increased to 0.27 (+/-0.04) mm yr-1 in 2000. This indicates that existing studies have substantially overestimated the contribution of GWD to global sea-levelrise by a cumulative amount of at least 10 mm during the twentieth century and early twenty-first century. With other terrestrial water contributions included, we estimate the net terrestrial water contribution during the period 1993-2010 to be +0.12 (+/-0.04) mm yr-1, suggesting that the net terrestrial water contribution reported in the IPCC Fifth Assessment Report report is probably overestimated by a factor of three.

Low-lying reef islands on the rim of atolls are perceived as particularly vulnerable to the impacts of sea-levelrise. Three effects are inferred: erosion of the shoreline, inundation of low-lying areas, and saline intrusion into the freshwater lens. Regional reconstruction of sea-level trends, supplementing the short observational instrumental record, indicates that monthly mean sealevel is rising in the eastern Indian and western Pacific Oceans. This paper reviews the morphology and substrate characteristics of reef islands on Indo-Pacific atolls, and summarises their topography. On most atolls across this region, there is an oceanward ridge built by waves to a height of around 3 m above MSL; in a few cases these are topped by wind-blown dunes. The prominence of these ridges, together with radiocarbon dating and multi-temporal studies of shoreline position, indicate net accretion rather than long-term erosion on most of these oceanward shores. Less prominent lagoonward ridges occur, but their morphology and continuity are atoll-specific, being a function of the processes operating in each lagoon. Low-lying central areas are a feature of many islands, often locally excavated for production of taro. These lower-lying areas are already subject to inundation, which seems certain to increase as the sea rises. Tropical storms play an important role in the geomorphology of reef islands in those regions where they are experienced. Topographical differences, as well as features such as emergence of the reef flat and the stability of the substrate, mean that islands differ in terms of their susceptibility to sea-levelrise. Further assessment of variations in shoreline vulnerability based on topography and substrate could form the basis for enhancing the natural resilience of these islands.

Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-levelrise to threatened and endangered species. Therefore, we estimated the impacts of risingsealevels on the endangered Lower Keys marsh rabbit ( Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-levelrise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-levelrise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.

As a low-lying peninsula surrounded by water, Florida faces tough decisions about long-range planning and development strategies to address impacts of climate change. In 2007, the Intergovernmental Panel on Climate Change (IPCC) stated there is strong evidence that global average sealevel will rise by ? to 2 feet in the next century due to continued thermal expansion and melting of ice on land.

Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-levelrise to threatened and endangered species. Therefore, we estimated the impacts of risingsealevels on the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-levelrise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-levelrise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.

Hurricane Sandy caused 43 fatalities in New York City and 19 billion in damages. Mayor Michael Bloomberg responded by convening the second New York City Panel on Climate Change (NPCC2), to provide up-to-date climate information for the City's Special Initiative for Rebuilding and Resiliency (SIRR). The Mayor's proposed 20 billion plan aims to strengthen the City's resilience to coastal inundation. Accordingly, the NPCC2 scientific and technical support team generated a suite of temperature, precipitation, and sealevelrise and extreme event projections through the 2050s. The NPCC2 sealevelrise projections include contributions from ocean thermal expansion, dynamic changes in sea surface height, mass changes in glaciers, ice caps, and ice sheets, and land water storage. Local sealevel changes induced by changes in ice mass include isostatic, gravitational, and rotational effects. Results are derived from CMIP5 model-based outputs, expert judgment, and literature surveys. Sealevel at the Battery, lower Manhattan, is projected to rise by 7-31 in (17.8-78.7cm) by the 2050s relative to 2000-2004 (10 to 90 percentile). As a result, flood heights above NAVD88 for the 100-year storm (stillwater plus waves) would rise from 15.0 ft (0.71 m) in the 2000s to 15.6-17.6 ft (4.8-5.4 m) by the 2050s (10-90 percentile). The annual chance of today's 100-year flood would increase from 1 to 1.4-5.0 percent by the 2050s.

From the shores of Bangladesh to the bayous of Louisiana, sealevelrise will affect communities across the globe and will likely be exacerbated by other threats such as severe weather. Local and national decision makers face a myriad of challenges as they prepare for or adapt to changing coastal conditions while trying to manage increasing population and development along the coasts. In the United States alone, approximately 39% of the population lives in a coastal county.

The contributions from terrestrial water sources to sea-levelrise, other than ice caps and glaciers, are highly uncertain and heavily debated1-5. Recent assessments indicate that groundwater depletion (GWD) may become the most important positive terrestrial contribution6-10 over the next 50 years, probably equal in magnitude to the current contributions from glaciers and ice caps6. However, the existing estimates assume that nearly 100% of groundwater extracted eventually ends up in the oceans. Owing to limited knowledge of the pathways and mechanisms governing the ultimate fate of pumped groundwater, the relative fraction of global GWD that contributes to sea-levelrise remains unknown. Here, using a coupled climate-hydrological model11,12 simulation, we show that only 80% of GWDends up in the ocean. An increase in runo to the ocean accounts for roughly two-thirds, whereas the remainder results from the enhanced net flux of precipitation minus evaporation over the ocean, due to increased atmospheric vapour transport from the land to the ocean. The contribution of GWD to global sea-levelrise amounted to 0.02 (+/- 0.004)mm yr(sup-1) in 1900 and increased to 0.27 (+/- 0.04)mm yr(sup-1) in 2000. This indicates that existing studies have substantially overestimated the contribution of GWD to global sea-levelrise by a cumulative amount of at least 10 mm during the twentieth century and early twenty-first century. With other terrestrial water contributions included, we estimate the net terrestrial water contribution during the period 1993-2010 to be +0.12 +/-0.04)mm yr(sup-1), suggesting that the net terrestrialwater contribution reported in the IPCC Fifth Assessment Report report is probably overestimated by a factor of three.

.8 mm yr-1, respectively. While the temporal pattern of the rate estimates is consistent with acceleration in sealevelrise, it may not be significant, as the uncertainties for the shorter analysis periods may not capture the full range of temporal variation. Analysis of the available continuous GPS records that have been collected within 80 km of Australian tide gauges suggests that rates of vertical crustal motion are generally low, with the majority of sites showing motion statistically insignificant from zero. A notable exception is the significant component of vertical land motion that contributes to the rapid rate of relative sealevel change (>4 mm yr-1) at the Hillarys site in the Perth area. This corresponds to crustal subsidence that we estimate in our GPS analysis at a rate of -3.1 ± 0.7 mm yr-1, and appears linked to groundwater withdrawal. Uncertainties on the rates of vertical displacement at GPS sites collected over a decade are similar to what we measure in several decades of tide gauge data. Our results motivate continued observations of relative sealevel using tide gauges, maintained with high-accuracy terrestrial and continuous co-located satellite-based surveying.

Data from salt marshes in the U.S. Southeast show that long-term variations in salt marsh productivity and porewater salinity correlate strongly with mean water level (MWL). To understand how tidally-influenced groundwater flow might control these correlations, we developed process-based numerical models to assess the effect of variations in MWL on groundwater flushing in salt marshes. We modeled homogeneous and layered marsh stratigraphy and compared flat and sloped topography for the marsh surface. Model results show that increases in MWL cause groundwater flushing to increase if greater areas of the marsh become inundated at high tide. Once the marsh was fully inundated at high tide, further increases in MWL caused groundwater flushing to decrease. We also investigated a range of tidal amplitudes, finding that increases in tidal amplitude increased groundwater flushing, particularly when increasing the tidal amplitude caused the marsh platform to be inundated at high tide. Results suggest that small increases in MWL associated with sealevelrise could increase increase productivity in marshes that are equilibrated near mean high water, but risingsealevel could decrease productivity, and thus accretion rates, in marshes that are equilibrated lower in the tidal frame. We speculate that the early stages of rising relative sealevel may also significantly impact water quality in bar-built estuaries (not river-dominated) by increasing groundwater flushing and thus raising the discharge of nutrients from coastal wetlands.

Historical aerial photographs, from 1937 to the present, show Skagit Delta tidal marshes prograding into Skagit Bay for most of the record, but the progradation rates have been steadily declining and the marshes have begun to erode in recent decades despite the large suspended sediment load provided by the Skagit River. In an area of the delta isolated from direct riverine sediment supply by anthropogenic blockage of historical distributaries, 0.5-m tall marsh cliffs along with concave marsh profiles indicate wave erosion is contributing to marsh retreat. This is further supported by a “natural experiment” provided by rocky outcrops that shelter high marsh in their lee, while being bounded by 0.5-m lower eroded marsh to windward and on either side. Coastal wetlands with high sediment supply are thought to be resilient to sealevelrise, but the case of the Skagit Delta shows this is not necessarily true. A combination of sealevelrise and wave-generated erosion may overwhelm sediment supply. Additionally, anthropogenic obstruction of historical distributaries and levee construction along the remaining distributaries likely increase the jet momentum of river discharge, forcing much suspended sediment to bypass the tidal marshes and be exported from Skagit Bay. Adaptive response to the threat of climate change related sealevelrise and increased wave frequency or intensity should consider the efficacy of restoring historical distributaries and managed retreat of constrictive river levees to maximize sediment delivery to delta marshes.

The investigation of future climate impacts at the coast requires sufficiently detailed projections for the nearshore waves and sealevels in both the present day and a future climate scenario, to provide an offshore boundary condition. Here we discuss the future changes in surge and wave climate forced by winds and pressures from a version of the Met Office Hadley Centre Climate model, for various greenhouse gas emission scenarios and for various climate model parameter choices. The local spatial variation in mean sealevel is also taken into account, incorporating deviations from global mean sealevel change caused by regional variations in ocean density and circulation. Some parts of the UK are still subject to glacial isostatic readjustment after the last ice age, counter-acting sealevelrise, although this will be overwhelmed by the projected effects of sealevelrise due to global warming in the 21st century, for most future emission scenarios. Model downscaling from the global coupled atmosphere-ocean model using a regional climate model is needed to provide more realistic and detailed wind simulations over the NW European continental shelf. There is large uncertainty in projected changes in storminess for the NE Atlantic region, with different climate models providing conflicting results for the future. Results from this study show that large increases in mean sealevel (even up to 5 metres) have very little effect on the dynamics of extreme surge events, the primary effect being on the speed of propagation of tide and surge (Howard et al., 2010). Increasing storminess is expected to increase surge heights but more direct effects can be attributed directly to increased mean sealevel. Based on the wave model results, seasonal mean and annual maximum wave heights are generally expected to increase to the SW of the UK, reduce to the north of the UK and experience little change in the southern North Sea or eastern Irish Sea. This pattern is consistent with a

In the U.S. Northeast, salt marshes are exceptionally vulnerable to the effects of acceleratedsealevelrise as compensatory mechanisms relying on positive feedbacks between inundation and sediment deposition are insufficient to counter inundation increases in low turbidity tida...

Global sealevelrise has certainly accelerated through the 21st and far beyond the previous projections and will continue to rise, while the frequencies and strength of extreme events such like flood and storm will increase due to global warming. Coastal cities where always be with densely population and accumulated social wealth will be under enormous affects. Using Landsat TM/ETM+ satellite images (1990, 2010) to extract urban built-up area, 17 China's developed coastal cities, which account for only 1.2% of total land area but boast 18.3% of urban population and nearly 19.6% of GDP in 2010, are spotted a 550% increase of urban land from 1990 to 2010. Shuttle Radar Topography Mission (SRTM) with 90m resolution data were used to calculate average elevation of extracted urban area. Then we found that these cities are all expanding seaward, occupying the most vulnerable neighborhoods, often in low-lying areas, alongside waterways prone to flooding. 11 cities show a reducing trend of mean elevations with the total average of more than 3 meters. Particularly, Shanghai, Tianjin and Ningbo in Delta area are most serious with the mean urban elevation less than 5 meters in 2010. The rapid expansion to seawards and accumulation of population and social wealth processed in coastal cities will increase the vulnerability and exposure, which will exacerbated the existing risks of risingsealevel or extreme events. Referring to Defense Meteorological Satellite Program (DMSP/OLS) city-lights data and SRTM data, we built the Urban Vulnerability Index (UVI) to do semi-quantitative assessment on vulnerabilities of coastal cities. The UVI case study in GuangZhou showed the most vulnerability region concentrated at the low-lying south area where is with the much higher relative South Sealevel than other sea area of China. With relative sealevelrise of 1-1.5 m by 2100 and increased frequency of extreme sealevel due to cyclone propagation, and weak urban drain-off system, Chinese

Both the rate and causes of twentieth century global sea-levelrise (GSLR) have been controversial. Estimates from tide-gauges range from less than one, to more than two millimetre yr(-1). In contrast, values based on the processes mostly responsible for GSLR-mass increase (from mountain glaciers and the great high latitude ice masses) and volume increase (expansion due to ocean warming)-fall below this range. Either the gauge estimates are too high, or one (or both) of the component estimates is too low. Gauge estimates of GSLR have been in dispute for several decades because of vertical land movements, especially due to glacial isostatic adjustment (GIA). More recently, the possibility has been raised that coastal tide-gauges measure exaggerated rates of sea-levelrise because of localized ocean warming. Presented here are two approaches to a resolution of these problems. The first is morphological, based on the limiting values of observed trends of twentieth century relative sea-levelrise as a function of distance from the centres of the ice loads at last glacial maximum. This observational approach, which does not depend on a geophysical model of GIA, supports values of GSLR near 2 mm yr(-1). The second approach involves an analysis of long records of tide-gauge and hydrographic (in situ temperature and salinity) observations in the Pacific and Atlantic Oceans. It was found that sea-level trends from tide-gauges, which reflect both mass and volume change, are 2-3 times higher than rates based on hydrographic data which reveal only volume change. These results support those studies that put the twentieth century rate near 2 mm yr(-1), thereby indicating that mass increase plays a much larger role than ocean warming in twentieth century GSLR.

Coastal flood damage and adaptation costs under 21st century sea-levelrise are assessed on a global scale taking into account a wide range of uncertainties in continental topography data, population data, protection strategies, socioeconomic development and sea-levelrise. Uncertainty in global mean and regional sealevel was derived from four different climate models from the Coupled Model Intercomparison Project Phase 5, each combined with three land-ice scenarios based on the published range of contributions from ice sheets and glaciers. Without adaptation, 0.2-4.6% of global population is expected to be flooded annually in 2100 under 25-123 cm of global mean sea-levelrise, with expected annual losses of 0.3-9.3% of global gross domestic product. Damages of this magnitude are very unlikely to be tolerated by society and adaptation will be widespread. The global costs of protecting the coast with dikes are significant with annual investment and maintenance costs of US$ 12-71 billion in 2100, but much smaller than the global cost of avoided damages even without accounting for indirect costs of damage to regional production supply. Flood damages by the end of this century are much more sensitive to the applied protection strategy than to variations in climate and socioeconomic scenarios as well as in physical data sources (topography and climate model). Our results emphasize the central role of long-term coastal adaptation strategies. These should also take into account that protecting large parts of the developed coast increases the risk of catastrophic consequences in the case of defense failure.

The '100-year flood' - formally defined as a flood with 0.01 annual probability - is a standard policy and regulatory benchmark for risk in the United States. However, there is increasing recognition that the traditional concept does not apply in a warming world. This is particularly the case with respect to coastal flooding, because at most locations, sealevelrise is increasing the risk of flooding to any given height with each passing decade. Here we propose a flexible approach to defining extreme coastal flood height that employs different periods of interest and takes changing risks into account, while maintaining some consistency with the legacy definition. We note that in a stationary world, a 0.01 annual chance flood is equivalent to a flood with cumulative probability P(N) = 1 - 0.99^N over a period of N years. We compute P(N) for N=1 to 100 years, and then estimate the corresponding extreme coastal flood height H(N) for each period length, taking into account projected local sealevelrise at each of 55 water level stations distributed throughout the contiguous US, and employing various sealevelrise scenarios. In one result, employing a 50-yr interval and the high-intermediate global sealevel scenario developed for the National Climate Assessment, we find that the height of extreme floods increases by an average of roughly 0.4 m or 40%, as compared to the traditional definition that assumes unchanging risk. Such discrepancies are compounded when we estimate extreme flood risk under the new approach as it would be calculated for periods beginning in future years, leading to rapid expansion of 100-year flood risk zones.

Climate warming due to the enhanced greenhouse effect is expected to have a significant impact on natural environment and human activity in high latitudes. Mostly, it should have a positive effect on human activity. The main threats in Estonia that could be connected with sea-levelrise are the flooding of coastal areas, erosion of sandy beaches and the destruction of harbour constructions. Possible climate change and its negative impacts in the coastal regions of Estonia are estimated in this paper. Climate change scenarios for Estonia were generated using a Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC) and a regional climate change database—SCENanario GENerator (SCENGEN). Three alternative emission scenarios were combined with data from 14 general circulation model experiments. Climate change scenarios for the year 2100 indicate a significant increase in air temperature (by 2.3-4.5 °C) and precipitation (by 5-30%) in Estonia. The highest increase is expected to take place during winter and the lowest increase in summer. Due to a long coastline (3794 km) and extensive low-lying coastal areas, global climate change through sea-levelrise will strongly affect the territory of Estonia. A number of valuable natural ecosystems will be in danger. These include both marine and terrestrial systems containing rare plant communities and suitable breeding places for birds. Most sandy beaches high in recreational value will disappear. However, isostatic land uplift and the location of coastal settlements at a distance from the present coastline reduce the rate of risk. Seven case study areas characterising all the shore types of Estonia have been selected for sea-levelrise vulnerability and adaptation assessment. Results and estimates of vulnerability to 1.0-m sea-levelrise by 2100 are presented in this paper. This is the maximum scenario according to which the actually estimated relative sea-levelrise would vary from 0.9 m (SW Estonia) to 0

The Grand Bay estuary, situated along the border of Alabama and Mississippi, is a marine dominant estuary. Juncus roemerianus and Spartina alterniflora cover approximately 49% of the estuary (Eleuterius and Criss, 1991); However, this marsh system is prone to erosion more than other marsh systems in the state (Mississippi Department of Marine Resources 1999). Water level and wind-driven waves are critical factors that cause erosion in the Grand Bay estuary. Sediment transport induced by wave forces from the Gulf of Mexico and sealevelrise force salt marshes to migrate landward (Schmid 2000). Understanding projected variations in vegetation can aid in productive restoration planning and coastal management decisions. An integrated hydro-marsh model was developed to incorporate the dynamic interaction between tidal hydrodynamics and salt marsh system. This model projects salt marsh productivity by coupling a two-dimensional, depth-integrated ADvanced CIRCulation (ADCIRC) finite element model and a parametric marsh model (Morris et al., 2002). The model calculates marsh productivity as a function of mean low water (MLW), mean high water (MHW), and the elevation of the marsh platform. The coupling exchange process is divided into several time intervals that capture the rate of sealevelrise, and update the elevation and bottom friction from the computed marsh productivity. Accurate description of salt marsh platform is necessary for calculating accurate biomass results (Hagen et al. 2013). Lidar-derived digital elevation models (DEM) over-estimate marsh platform elevations, but can be corrected with Real Time Kinematic (RTK) survey data (Medeiros et al., 2015). Using RTK data, the salt marsh platform was updated and included in a high resolution hydrodynamic model. Four projections of sealevelrise (Parris et al., 2012) were used to project salt marsh productivity for the year 2100 for the Grand Bay, MS estuary. The results showed a higher productivity under low sea

Over the past decade, ice loss from the Greenland Ice Sheet increased as a result of both increased surface melting and ice discharge to the ocean. The latter is controlled by the acceleration of ice flow and subsequent thinning of fast-flowing marine-terminating outlet glaciers. Quantifying the future dynamic contribution of such glaciers to sea-levelrise (SLR) remains a major challenge because outlet glacier dynamics are poorly understood. Here we present a glacier flow model that includes a fully dynamic treatment of marine termini. We use this model to simulate behaviour of four major marine-terminating outlet glaciers, which collectively drain about 22 per cent of the Greenland Ice Sheet. Using atmospheric and oceanic forcing from a mid-range future warming scenario that predicts warming by 2.8 degrees Celsius by 2100, we project a contribution of 19 to 30 millimetres to SLR from these glaciers by 2200. This contribution is largely (80 per cent) dynamic in origin and is caused by several episodic retreats past overdeepenings in outlet glacier troughs. After initial increases, however, dynamic losses from these four outlets remain relatively constant and contribute to SLR individually at rates of about 0.01 to 0.06 millimetres per year. These rates correspond to ice fluxes that are less than twice those of the late 1990s, well below previous upper bounds. For a more extreme future warming scenario (warming by 4.5 degrees Celsius by 2100), the projected losses increase by more than 50 per cent, producing a cumulative SLR of 29 to 49 millimetres by 2200.

Climate change and sealevelrise (SLR) are global impacts threatening the sustainability of coastal territories and valuable ecosystems such as deltas. The Ebro Delta is representative of the vulnerability of coastal areas to SLR. Rice cultivation is the main economic activity in the region. Rice fields occupy most of the delta (ca. 65%) and are vulnerable to accelerated SLR and consequent increase in soil salinity, the most important physical factor affecting rice production. We developed a model to predict the impacts of SLR on soil salinity and rice production under different scenarios predicted by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change by coupling data from Geographic Information Systems with Generalized Linear Models. Soil salinity data were measured in agricultural parcels and rice production from surveys among farmers. The correlation between observed and soil salinity predicted values was high and significant (Pearson's r=0.72, P<0.0001), thus supporting the predictive ability of the model. Soil salinity was directly related to distances to the river, to the delta inner border, and to the river old mouth, while clay presence, winter river flow and surface elevation were inversely related to it. Surface elevation was the most important variable in explaining soil salinity. Rice production was negatively influenced by soil salinity, thus the models predict a decrease from higher elevation zones close to the river to the shoreline. The model predicts a maximum reduction in normalized rice production index from 61.2% in 2010 to 33.8% by 2100 in the worst considered scenario (SLR=1.8m), with a decrease of profit up to 300 € per hectare. The model can be applied to other deltaic areas worldwide, and help rice farmers and stakeholders to identify the most vulnerable areas to SLR impacts.

Since the Mid-Holocene, some 5000 years ago, coral reefs in the Pacific Ocean have been vertically constrained by sealevel. Contemporary sea-levelrise is releasing these constraints, providing accommodation space for vertical reef expansion. Here, we show that Porites microatolls, from reef-flat environments in Palau (western Pacific Ocean), are 'keeping up' with contemporary sea-levelrise. Measurements of 570 reef-flat Porites microatolls at 10 locations around Palau revealed recent vertical skeletal extension (78±13 mm) over the last 6-8 years, which is consistent with the timing of the recent increase in sealevel. We modelled whether microatoll growth rates will potentially 'keep up' with predicted sea-levelrise in the near future, based upon average growth, and assuming a decline in growth for every 1°C increase in temperature. We then compared these estimated extension rates with rates of sea-levelrise under four Representative Concentration Pathways (RCPs). Our model suggests that under low-mid RCP scenarios, reef-coral growth will keep up with sea-levelrise, but if greenhouse gas concentrations exceed 670 ppm atmospheric CO2 levels and with +2.2°C sea-surface temperature by 2100 (RCP 6.0 W m(-2)), our predictions indicate that Porites microatolls will be unable to keep up with projected rates of sea-levelrise in the twenty-first century.

Coastal responses to sealevelrise (SLR) include inundation of wetlands, increased shoreline erosion, and increased flooding during storm events. Hydrodynamic parameters such as tidal ranges, tidal prisms, tidal asymmetries, increased flooding depths and inundation extents during storm events respond nonadditively to SLR. Coastal morphology continually adapts toward equilibrium as sealevelsrise, inducing changes in the landscape. Marshes may struggle to keep pace with SLR and rely on sediment accumulation and the availability of suitable uplands for migration. Whether hydrodynamic, morphologic, or ecologic, the impacts of SLR are interrelated. To plan for changes under future sealevels, coastal managers need information and data regarding the potential effects of SLR to make informed decisions for managing human and natural communities. This review examines previous studies that have accounted for the dynamic, nonlinear responses of hydrodynamics, coastal morphology, and marsh ecology to SLR by implementing more complex approaches rather than the simplistic “bathtub” approach. These studies provide an improved understanding of the dynamic effects of SLR on coastal environments and contribute to an overall paradigm shift in how coastal scientists and engineers approach modeling the effects of SLR, transitioning away from implementing the “bathtub” approach. However, it is recommended that future studies implement a synergetic approach that integrates the dynamic interactions between physical and ecological environments to better predict the impacts of SLR on coastal systems.

Using a global model of continental water balance, forced by interannual variations in precipitation and near-surface atmospheric temperature for the period 1981-1998, we estimate the sea-level changes associated with climate-driven changes in storage of water as snowpack, soil water, and ground water; storage in ice sheets and large lakes is not considered. The 1981-1998 trend is estimated to be 0.12 mm/yr, and substantial interannual fluctuations are inferred; for 1993-1998, the trend is 0.25 mm/yr. At the decadal time scale, the terrestrial contribution to eustatic (i.e., induced by mass exchange) sea-levelrise is significantly smaller than the estimated steric (i.e., induced by density changes) trend for the same period, but is not negligibly small. In the model the sea-levelrise is driven mainly by a downtrend in continental precipitation during the study period, which we believe was generated by natural variability in the climate system.

The timing and evolution of Jabat Island, Marshall Islands, was investigated using morphostratigraphic analysis and radiometric dating. Results show the first evidence of island building in the Pacific during latter stages of Holocene sealevelrise. A three-phase model of development of Jabat is presented. Initially, rapid accumulation of coarse sediments on Jabat occurred 4800-4000 years B.P. across a reef flat higher than present level, as sealevel continued to rise. During the highstand, island margins and particularly the western margin accreted vertically to 2.5-3.0 m above contemporary ridge elevations. This accumulation phase was dominated by sand-size sediments. Phase three involved deposition of gravel ridges on the northern reef, as sealevel fell to present position. Jabat has remained geomorphically stable for the past 2000 years. Findings suggest reef platforms may accommodate the oldest reef islands in atoll systems, which may have profound implications for questions of prehistoric migration through Pacific archipelagos.

Coastal responses to sealevelrise (SLR) include inundation of wetlands, increased shoreline erosion, and increased flooding during storm events. Hydrodynamic parameters such as tidal ranges, tidal prisms, tidal asymmetries, increased flooding depths and inundation extents during storm events respond nonadditively to SLR. Coastal morphology continually adapts toward equilibrium as sealevelsrise, inducing changes in the landscape. Marshes may struggle to keep pace with SLR and rely on sediment accumulation and the availability of suitable uplands for migration. Whether hydrodynamic, morphologic, or ecologic, the impacts of SLR are interrelated. To plan for changes under future sealevels, coastal managers need information and data regarding the potential effects of SLR to make informed decisions for managing human and natural communities. This review examines previous studies that have accounted for the dynamic, nonlinear responses of hydrodynamics, coastal morphology, and marsh ecology to SLR by implementing more complex approaches rather than the simplistic "bathtub" approach. These studies provide an improved understanding of the dynamic effects of SLR on coastal environments and contribute to an overall paradigm shift in how coastal scientists and engineers approach modeling the effects of SLR, transitioning away from implementing the "bathtub" approach. However, it is recommended that future studies implement a synergetic approach that integrates the dynamic interactions between physical and ecological environments to better predict the impacts of SLR on coastal systems.

The Intergovernmental Panel on Climate Change (IPCC) estimates that the sum of all contributions to sea-levelrise for the period 1961-2004 was 1.1 ± 0.5 mm a-1, leaving 0.7 ± 0.7 of the 1.8 ± 0.5 mm a-1 observed sea-levelrise unexplained. Here, we compute the global surface mass balance of all mountain glaciers and ice caps (MG&IC), and find that part of this much-discussed gap can be attributed to a larger contribution than previously assumed from mass loss of MG&IC, especially those around the Antarctic Peninsula. We estimate global surface mass loss of all MG&IC as 0.79 ± 0.34 mm a-1 sea-level equivalent (SLE) compared to IPCC's 0.50 ± 0.18 mm a-1. The Antarctic MG&IC contributed 28% of the global estimate due to exceptional warming around the Antarctic Peninsula and high sensitivities to temperature similar to those we find in Iceland, Patagonia and Alaska.

Understanding the hydrodynamics in estuaries with respect to magnitudes of sea-levelrise is important to comprehend the changes of distinct physical processes which are coupled among each other. The current state of the lagoons and rivers of the Papaloapan estuary, Ver., is studied in order to identify these processes and have a base line with which compare different sea-levelrise and hydrological regimes scenarios, with particular attention in the average salt content, its change in different zones, and the intrusion length into the rivers. For this purpose, hydrography, water level, salinity, bathymetry, and current measurements were carried out, complementary to this, a coastal ocean model is implemented to study the response of the region to a sealevel increase. Six oceanographic expeditions in which 49 stations of CTD were carried out and 11 thermistors were placed, it was found that the major tidal components are O1 and K1, with an amplitude of 13.5 and 12.3 cm respectively in the channel, followed by the Q1, N2 and S2 components according to the amplitude. Salt content upstream the rivers show more increase in the dry period than in the wet period of the year. In addition, hydrographic data show that in most of the surveys, Camaronera lagoon had larger salinity than Buen Pais, Alvarado and Tlalixcoyan lagoons.

The rate of global sealevel change over the past hundred years has been considered a quantity of paramount importance in the context of climate change, as can be noted from the Intergovernmental Panel on Climate Change (IPCC) reports. The range of estimates published so far is relatively large, mostly between 1 and 2 mm/year. Some of them are, however, inconsistent with each other at the 95% confidence level of a few tenths of millimetre pear year (see Spada and Galassi 2012, and references therein). Tide gauge records remain the primary source of sealevel information over multi-decadal to century timescales, precise satellite altimetry data being available only since the 1990s. A critical issue in using this type of data to determine climate-related contributions to sealevel change concerns the vertical motion of the land upon which the gauges are grounded. To correct the data for this vertical motion, most previous studies have been based on models of glacial isostatic adjustment (GIA); thus assuming that the other processes causing vertical displacements at the subset of tide gauge records selected are negligible and/or cancel out in the average. Here we use observations from the Global Positioning System (GPS) instead of GIA model predictions for the correction of vertical land motion at tide gauges. As a result, the spatial coherence in the rates of sealevel change is substantially increased, ultimately revealing a clearly distinct behaviour between the northern and the southern hemispheres with estimates of 2.0 mm/year and 1.1 mm/year, respectively. Our findings underscore that vertical land movement at tide gauges is an important source of spatial variability in the rates of sealevel change. It prevents from extracting climate-related fingerprints if not taken into account adequately. Furthermore, while our results somewhat challenge the widely accepted value of global sealevelrise for the 20th century, they also reconcile the past estimates by

Increases in the elevation of the soil surfaces of mangroves and salt marshes are key to the maintenance of these habitats with acceleratingsealevelrise. Understanding the processes that give rise to increases in soil surface elevation provides science for management of landscapes for sustainable coastal wetlands. Here, we tested whether the soil surface elevation of mangroves and salt marshes in Moreton Bay is keeping up with local rates of sealevelrise (2.358 mm y-1) and whether accretion on the soil surface was the most important process for keeping up with sealevelrise. We found variability in surface elevation gains, with sandy areas in the eastern bay having the highest surface elevation gains in both mangrove and salt marsh (5.9 and 1.9 mm y-1) whereas in the muddier western bay rates of surface elevation gain were lower (1.4 and -0.3 mm y-1 in mangrove and salt marsh, respectively). Both sides of the bay had similar rates of surface accretion (~7–9 mm y-1 in the mangrove and 1–3 mm y-1 in the salt marsh), but mangrove soils in the western bay were subsiding at a rate of approximately 8 mm y-1, possibly due to compaction of organic sediments. Over the study surface elevation increments were sensitive to position in the intertidal zone (higher when lower in the intertidal) and also to variation in mean sealevel (higher at high sealevel). Although surface accretion was the most important process for keeping up with sealevelrise in the eastern bay, subsidence largely negated gains made through surface accretion in the western bay indicating a high vulnerability to sealevelrise in these forests.

Coral atolls are stunning both for their beauty and for their geomorphic organization. In addition, these islands are home to hundreds of thousands of people, and are threatened by both risingsealevel and increasing ocean acidification. However, it has been suggested that the same geomorphic processes that formed these islands may continue to provide sediment at a rate sufficient to keep them above a risingsealevel. A quantitative assessment of this hypothesis requires a numerical model that must first pass the test of being able to simulate the fundamental geomorphic and sedimentary structural features of a classic atoll. Here we present the first unified landscape process and carbonate growth model to capture the key components of an atoll. The model includes carbonate growth functions modified by light limitation, ocean chemistry, and surf zone energy. It also includes a physically based wave model, erosion by wave action, as well as dissolution and sediment transport functions that serve to modify the subaerial landscape. The model is initialized with a bare volcanic island subsiding at a rate of 0.1mm/yr. We then run the model through multiple glacial - interglacial sealevel cycles. This model generates a landscape that matches the following atoll features: an annular island of loose sediment surrounded by a reef, gaps in this ring that are more abundant and larger on atolls with larger diameters, and a deep interior lagoon filled with a combination of autochthonous sediments as well as material transported inward from the outer reef. In addition, the island symmetry shifts in response to predominant wind-wave directions — large islands build on the windward side; islands are small or non-existent in the lee. While this model is not yet suitable for predictions of the fate of specific islands, it does suggest some general rules. If no substantial changes to the system occur, some of these islands may be able to keep pace with risingsealevel; however

Substantial retreat of the Antarctic Ice Sheet during past warm periods including the Pliocene and some Pleistocene interglacials has been difficult to reconcile in most ice sheet models. This includes the Last Interglacial (LIG; ~130 to 115 ka), when Antarctica is now thought to have contributed +4 to +7m of equivalent sea-levelrise. Here we use a continental ice sheet-shelf model with new physics accounting for structural failure of large tidewater ice cliffs and the influence of surface meltwater on ice-shelf calving. Coupled with high-resolution atmosphere and ocean components, the model is used to simulate the Antarctic Ice Sheet under Pliocene, LIG, and future conditions. The new model simulates an Antarctic contribution to sea-levelrise of ~15m during peak mid-Pliocene warmth and ~4.25m during the LIG, in approximate agreement with (albeit uncertain) geological sea-level indicators. When applied to long-term future simulations assuming extended RCP greenhouse gas emission scenarios and using high resolution atmosphere and ocean components, the same model physics show a dramatic retreat of Antarctic marine-based ice over the next 500 years, beginning within a few decades in the Pine Island Bay sector of West Antarctica. In the most extreme RCP scenarios, subsequent retreat of the Siple Coast margin results in the near-total collapse of the West Antarctic Ice Sheet (WAIS) within a few centuries, followed by retreat into the deep subglacial basins underlying the East Antarctic Ice Sheet (EAIS). Antarctica is shown to contribute up to 9m of sealevelrise within the next five centuries. Under such high greenhouse gas conditions, atmospheric warming alone is sufficient to cause substantial ice retreat, without any influence from ocean warming and sub-ice melt. Conversely, in the absence of increasing atmospheric temperatures, very little ocean warming (<0.5 C) is required to trigger substantial WAIS retreat, even if present-day atmospheric temperatures are held

Temperatures within shallow reefs often differ substantially from those in the surrounding ocean; therefore, predicting future patterns of thermal stresses and bleaching at the scale of reefs depends on accurately predicting reef heat budgets. We present a new framework for quantifying how tidal and solar heating cycles interact with reef morphology to control diurnal temperature extremes within shallow, tidally forced reefs. Using data from northwestern Australia, we construct a heat budget model to investigate how frequency differences between the dominant lunar semidiurnal tide and diurnal solar cycle drive ~15-day modulations in diurnal temperature extremes. The model is extended to show how reefs with tidal amplitudes comparable to their depth, relative to mean sealevel, tend to experience the largest temperature extremes globally. As a consequence, we reveal how even a modest sealevelrise can substantially reduce temperature extremes within tide-dominated reefs, thereby partially offsetting the local effects of future ocean warming. PMID:27540589

Standard approaches to determining the impacts of sealevelrise (SLR) on storm surge flooding employ numerical models reflecting present conditions with modified sea states for a given SLR scenario. In this study, we advance this paradigm by adjusting the model framework so that it reflects not only a change in sea state but also variations to the landscape (morphologic changes and urbanization of coastal cities). We utilize a numerical model of the Mississippi and Alabama coast to simulate the response of hurricane storm surge to changes in sealevel, land use/land cover, and land surface elevation for past (1960), present (2005), and future (2050) conditions. The results show that the storm surge response to SLR is dynamic and sensitive to changes in the landscape. We introduce a new modeling framework that includes modification of the landscape when producing storm surge models for future conditions.

We used a numerical model to investigate how a barrier island groundwater system responds to increases of up to 60 cm in sealevel. We found that a sea-levelrise of 20 cm leads to substantial changes in the depth of the water table and the extent and depth of saltwater intrusion, which are key determinants in the establishment, distribution and succession of vegetation assemblages and habitat suitability in barrier islands ecosystems. In our simulations, increases in water-table height in areas with a shallow depth to water (or thin vadose zone) resulted in extensive groundwater inundation of land surface and a thinning of the underlying freshwater lens. We demonstrated the interdependence of the groundwater response to island morphology by evaluating changes at three sites. This interdependence can have a profound effect on ecosystem composition in these fragile coastal landscapes under long-term changing climatic conditions.

Temperatures within shallow reefs often differ substantially from those in the surrounding ocean; therefore, predicting future patterns of thermal stresses and bleaching at the scale of reefs depends on accurately predicting reef heat budgets. We present a new framework for quantifying how tidal and solar heating cycles interact with reef morphology to control diurnal temperature extremes within shallow, tidally forced reefs. Using data from northwestern Australia, we construct a heat budget model to investigate how frequency differences between the dominant lunar semidiurnal tide and diurnal solar cycle drive ~15-day modulations in diurnal temperature extremes. The model is extended to show how reefs with tidal amplitudes comparable to their depth, relative to mean sealevel, tend to experience the largest temperature extremes globally. As a consequence, we reveal how even a modest sealevelrise can substantially reduce temperature extremes within tide-dominated reefs, thereby partially offsetting the local effects of future ocean warming.

In the 21st century coastal systems are subject to the pressures of centuries of population growth and resource exploitation. In 2003, in the US approximately 153 million people (53 percent of the population) lived in coastal counties, an increase of 33 million people since 1980 and this is expected to increase by approximately 7 million by the year 2008. Eight of the world's top ten largest cities are located at the coast, 44 % of the world's population (more people than inhabited the entire globe in 1950) live within 150 km of the coast and in 2001 over half the world's population lived within 200 km of a coastline. . Increased population density at the coasts often brings pollution and habitat degradation - decreasing the value of many of the resources that initially attract the coastal development - and it also means the effect of sea-levelrise on coastal geomorphic systems must be seen in the context of additional human pressures. For global sea-level debate centers on the magnitude and rate of the rise around most of the world; the exception being those areas still experiencing falling sea-levels due to isostatic rebound. Many coastal island states are clearly vulnerable. While the ‘lurid and misleading maps' of the 1980's used by many to indicate areas to be flooded by rising seas in the future, have been replaced by more considered discussion of the response of coastal dynamics to rising seas there is still considerable debate about the amount of sea-levelrise shorelines will experience in the 21st century. For coastal wetlands four main sets of physical factors - fine sediment regime; tidal conditions; coastal configuration; and relative sea-level change - define the geomorphic context for coastal marsh development and survival during the 21st century. Each of these factors is influenced by changes in climate and human alterations to coastal and inshore environments. In turn changes in sediment dynamics are mediated by both physical forcing and biotic

Atmospheric warming is projected to increase global mean surface temperatures by 0.3 to 4.8 degrees Celsius above present values by the end of this century (Collins et al., 2013). If anthropogenic emissions continue unchecked, the warming increase may reach 8-10 degrees Celsius by 2300 (Rogelj et al., 2012). The contribution that large ice sheets will make to sea-levelrise under such warming scenarios is difficult to quantify because the equilibrium-response timescale of ice sheets is longer than those of the atmosphere or ocean. Here we use a coupled ice-sheet/ice-shelf model to show that if atmospheric warming exceeds 1.5 to 2 degrees Celsius above present, collapse of the major Antarctic ice shelves triggers a centennial- to millennial-scale response of the Antarctic ice sheet in which enhanced viscous flow produces a long-term commitment (an unstoppable contribution) to sea-levelrise. Our simulations represent the response of the present-day Antarctic ice-sheet system to the oceanic and climatic changes of four representative concentration pathways (RCPs) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Collins et al., 2013). We find that substantial Antarctic ice loss can be prevented only by limiting greenhouse gas emissions to RCP 2.6 levels. Higher-emissions scenarios lead to ice loss from Antarctic that will raise sealevel by 0.6-3 metres by the year 2300. Our results imply that greenhouse gas emissions in the next few decades will strongly influence the long-term contribution of the Antarctic ice sheet to global sealevel.

Atmospheric warming is projected to increase global mean surface temperatures by 0.3 to 4.8 degrees Celsius above pre-industrial values by the end of this century. If anthropogenic emissions continue unchecked, the warming increase may reach 8-10 degrees Celsius by 2300 (ref. 2). The contribution that large ice sheets will make to sea-levelrise under such warming scenarios is difficult to quantify because the equilibrium-response timescale of ice sheets is longer than those of the atmosphere or ocean. Here we use a coupled ice-sheet/ice-shelf model to show that if atmospheric warming exceeds 1.5 to 2 degrees Celsius above present, collapse of the major Antarctic ice shelves triggers a centennial- to millennial-scale response of the Antarctic ice sheet in which enhanced viscous flow produces a long-term commitment (an unstoppable contribution) to sea-levelrise. Our simulations represent the response of the present-day Antarctic ice-sheet system to the oceanic and climatic changes of four representative concentration pathways (RCPs) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We find that substantial Antarctic ice loss can be prevented only by limiting greenhouse gas emissions to RCP 2.6 levels. Higher-emissions scenarios lead to ice loss from Antarctic that will raise sealevel by 0.6-3 metres by the year 2300. Our results imply that greenhouse gas emissions in the next few decades will strongly influence the long-term contribution of the Antarctic ice sheet to global sealevel.

Atmospheric warming is projected to increase global mean surface temperatures by 0.3 to 4.8 degrees Celsius above pre-industrial values by the end of this century. If anthropogenic emissions continue unchecked, the warming increase may reach 8-10 degrees Celsius by 2300 (ref. 2). The contribution that large ice sheets will make to sea-levelrise under such warming scenarios is difficult to quantify because the equilibrium-response timescale of ice sheets is longer than those of the atmosphere or ocean. Here we use a coupled ice-sheet/ice-shelf model to show that if atmospheric warming exceeds 1.5 to 2 degrees Celsius above present, collapse of the major Antarctic ice shelves triggers a centennial- to millennial-scale response of the Antarctic ice sheet in which enhanced viscous flow produces a long-term commitment (an unstoppable contribution) to sea-levelrise. Our simulations represent the response of the present-day Antarctic ice-sheet system to the oceanic and climatic changes of four representative concentration pathways (RCPs) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We find that substantial Antarctic ice loss can be prevented only by limiting greenhouse gas emissions to RCP 2.6 levels. Higher-emissions scenarios lead to ice loss from Antarctic that will raise sealevel by 0.6-3 metres by the year 2300. Our results imply that greenhouse gas emissions in the next few decades will strongly influence the long-term contribution of the Antarctic ice sheet to global sealevel.

Changes in the climate system's energy budget are predominantly revealed in ocean temperatures and the associated thermal expansion contribution to sea-levelrise. Climate models, however, do not reproduce the large decadal variability in globally averaged ocean heat content inferred from the sparse observational database, even when volcanic and other variable climate forcings are included. The sum of the observed contributions has also not adequately explained the overall multi-decadal rise. Here we report improved estimates of near-global ocean heat content and thermal expansion for the upper 300 m and 700 m of the ocean for 1950-2003, using statistical techniques that allow for sparse data coverage and applying recent corrections to reduce systematic biases in the most common ocean temperature observations. Our ocean warming and thermal expansion trends for 1961-2003 are about 50 per cent larger than earlier estimates but about 40 per cent smaller for 1993-2003, which is consistent with the recognition that previously estimated rates for the 1990s had a positive bias as a result of instrumental errors. On average, the decadal variability of the climate models with volcanic forcing now agrees approximately with the observations, but the modelled multi-decadal trends are smaller than observed. We add our observational estimate of upper-ocean thermal expansion to other contributions to sea-levelrise and find that the sum of contributions from 1961 to 2003 is about 1.5 +/- 0.4 mm yr(-1), in good agreement with our updated estimate of near-global mean sea-levelrise (using techniques established in earlier studies) of 1.6 +/- 0.2 mm yr(-1).

Sealevel lowering is commonly invoked as an important predisposing factor or potential trigger for sediment failure of unconsolidated sediment deposited during previous highstand conditions on continental shelves and slopes. However, studies from Quaternary continental margins increasingly document sediment failure during times of relative sealevelrise and hint to a more complex relation between changing sealevel and mass wasting. Three extensive mass-failure deposits originated during the late-Quaternary sealevelrise on the eastern Tyrrhenian margin and Strait of Sicily. The deposits that failed had markedly different architectures: offshore Cape Licosa, a shelf-margin lowstand wedge failed along its basal downlap surface; in Paola slope basin and in Gela Basin, extensive failure on the upper slope involved a few-m-thick mud drape and older consolidated units. Regardless of their geometric differences, all three failures occurred close to melt-water pulses (mwp1A, 1B), based on the timing of the onset of the post-slide drapes. This evidence suggests that rapid drowning of unconsolidated sediment resulted in increased water load, and enhanced pore pressure played a role in favouring failure. This view is consistent with the evidence that, in all three areas, failure coincides also with a marked change in sedimentation style. Such change reflects a substantial landward shift of sediment entry points and decrease in sediment accumulation rates, both consistent with the draped stile of post-failure deposition. We speculate that failure occurred in response to the following combination of predisposing factors and triggers: 1) during the Last Glacial Maximum, rapid deposition on the upper slope resulted in the formation of potentially unstable sediment sections resting on well defined basal surfaces; 2) when sealevelrise reached peak rates (mwp1A or mwp1B), hydrostatic load increased the pore pressure within the recently-deposited sediments; 3) this increase of

Relative sealevelrise (RSLR) due to climate change and geodynamics represents the main threat for the survival of Venice, emerging today only 90 cm above the Northern Adriatic mean sealevel (msl). The 25 cm RSLR occurred over the 20th century, consisting of about 12 cm of land subsidence and 13 cm of sealevelrise, has increased the flood frequency by more than seven times with severe damages to the urban heritage. Reasonable forecasts of the RSLR expected to the century end must be investigated to assess the suitability of the Mo.S.E. project planned for the city safeguarding, i.e., the closure of the lagoon inlets by mobile barriers. Here we consider three RSLR scenarios as resulting from the past sealevelrise recorded in the Northern Adriatic Sea, the IPCC mid-range A1B scenario, and the expected land subsidence. Available sealevel measurements show that more than 5 decades are required to compute a meaningful eustatic trend, due to pseudo-cyclic 7-8 year long fluctuations. The period from 1890 to 2007 is characterized by an average rate of 0.12 ± 0.01 cm/year. We demonstrate that linear regression is the most suitable model to represent the eustatic process over these 117 year. Concerning subsidence, at present Venice is sinking due to natural causes at 0.05 cm/year. The RSLR is expected to range between 17 and 53 cm by 2100, and its repercussions in terms of flooding frequency are associated here to each scenario. In particular, the frequency of tides higher than 110 cm, i.e., the value above which the gates would close the lagoon to the sea, will increase from the nowadays 4 times per year to a range between 20 and 250. These projections provide a large spread of possible conditions concerning the survival of Venice, from a moderate nuisance to an intolerable aggression. Hence, complementary solutions to Mo.S.E. may well be investigated.

Sealevelrise (SLR) threatens coastal environments with loss of land, inundation of coastal wetlands, and increased flooding during extreme storm events. Research has shown that SLR is a major factor in the long-term, gradual retreat of shorelines (Fitzgerald et al., 2008). Along sandy shorelines, retreat has a more dynamic effect than just inundation due to rising water levels, including the physical process of erosion in which sand is removed from the shoreface and deposited offshore. This has the potential to affect ecological habitats as well as coastal communities. Although SLR induces seaward retreat of shorelines, many shorelines especially within the vicinity of inlets may experience accretion due to sediment trapping or beach replenishment (Aubrey and Giese, 1993, Browder and R.G., 1999). This study examines the influence of including projected shoreline changes under future sea states into hydrodynamic modeling within the Northern Gulf of Mexico (NGOM). The NGOM coastline is an economically and ecologically significant area, comprised of various bays, barrier islands and mainland beaches. Projected shorelines and nearshore morphology for the year 2050 are derived from the Coastal Vulnerability Index (CVI) shoreline change rates (Thieler and Hammer-Klose, 1999) and used in conjunction with the 'Bruun Rule effect'(Bruun, 1962). A large scale hydrodynamic model forced by astronomic tides and hurricane winds and pressures is used to simulate present conditions, a high projection of the 2050 sea state (18 in of SLR in accordance with Parris et al. (2012)) and the 2050 high sea state with 2050 shorelines to test the sensitivity of the system to the projected shoreline changes. Results show that shoreline changes coupled with sealevelrise increases tidal inundation along shorelines, amplifies overtopping of barrier islands during storm surge events, and heightens inland storm surge inundation. It is critical to include estimates of shoreline and barrier

Barrier islands along the U.S. Gulf coast remain under increasing pressure from development. This development and redevelopment is occurring despite recent hurricanes, ongoing erosion, and sea-levelrise. To lessen the impacts of these hazards, local governments need information in a form that is useful for informing the public, making policy, and enforcing development rules. We recently completed the Galveston Island Geohazards Map for the city of Galveston, Texas and are currently developing maps for the Mustang and South Padre Island communities. The maps show areas that vary in their susceptibility to, and function for, mitigating the effects of geological processes, including sea-levelrise, land subsidence, erosion and storm-surge flooding and washover. The current wetlands, beaches and dunes are mapped as having the highest geohazard potential both in terms of their exposure to hazardous conditions and their mitigating effects of those hazards for the rest of the island. These existing “critical environments” are generally protected under existing regulations. Importantly, however, the mapping recognizes that sea-levelrise and shoreline retreat are changing the island; therefore, 60-year model projections of the effects of these changes are incorporated into the map. The areas that we project will become wetlands, beaches and dunes in the next 60 years are not protected. These areas are the most difficult to deal with from a policy point of view, yet we must address what happens there if real progress is to be made in how we live with sea-levelrise. The geohazards maps draw on decades of geological knowledge of how barrier islands behave and put it in a form that is intuitive to the public and directly useful to planners. Some of the “messages” in the map include: leave salt marshes alone and give them room to migrate inland as sealevelrises; set back and move development away from the shoreline to provide space for beaches and protective dunes

Malaysia consists of two major parts, a mainland on the Peninsular Malaysia and the East Malaysia on the Borneo Island. Their surrounding waters connect the Andaman Sea located northeast of the Indian Ocean to the Celebes Sea in the western tropical Pacific Ocean through the southern East Sea of Vietnam/South China Sea. As a result, inter-annual sealevel in the Malaysian waters is governed by various regional phenomena associated with the adjacent parts of the Indian and Pacific Oceans. We estimated sealevelrise (SLR) rate in the domain using tide gauge records often being gappy. To reconstruct the missing data, two methods are used: (i) correlating sealevel with climate indices El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD), and (ii) filling the gap using records of neighboring tide gauges. Latest vertical land movements have been acquired to derive geocentric SLR rates. Around the Peninsular Malaysia, geocentric SLR rates in waters of Malacca Strait and eastern Peninsular Malaysia during 1986-2011 are found to be 3.9±3.3 mm/year and 4.2 ± 2.5 mm/year, respectively; while in the East Malaysia waters the rate during 1988-2011 is 6.3 ± 4.0 mm/year. These rates are arguably higher than global tendency for the same periods. For the overlapping period 1993-2011, the rates are consistent with those obtained using satellite altimetry.

Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sealevel has been 6-9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics-including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs-that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-levelrise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.

Coastal protection design heights typically consider the superimposed effects of tides, surges, waves, and relative sea-levelrise (SLR), neglecting non-linear feedbacks between these forcing factors. Here, we use hydrodynamic modelling and multivariate statistics to show that shallow coastal areas are extremely sensitive to changing non-linear interactions between individual components caused by SLR. As sea-level increases, the depth-limitation of waves relaxes, resulting in waves with larger periods, greater amplitudes, and higher run-up; moreover, depth and frictional changes affect tide, surge, and wave characteristics, altering the relative importance of other risk factors. Consequently, sea-level driven changes in wave characteristics, and to a lesser extent, tides, amplify the resulting design heights by an average of 48–56%, relative to design changes caused by SLR alone. Since many of the world’s most vulnerable coastlines are impacted by depth-limited waves, our results suggest that the overall influence of SLR may be greatly underestimated in many regions. PMID:28057920

A succession of elevated ridge deposits on the south Florida margin was mapped using high-resolution seismic and side-scan sonar imaging in water depths ranging from 50 to 124 m. The ridges are interpreted to be subtidal shoal complexes and paleoshorelines (eolian dune or beach) formed during the last sea-level transgression. Oolitic and skeletal grainstones and mixed skeletal-peloidal-ooid packstones were recovered using a research submersible. All of the grains are of shallow-water or intertidal origin, and both marine and nonmarine cements were identified. Formation and preservation of these features are attributed to episodic and rapid changes in the rate of the deglacial sea-levelrise at the onset of the termination 1A ??18O excursion. This high-resolution record of sea-level change appears to be related to deglacial processes operating on submillennial time scales and supports increasing evidence of rapid episodic fluctuations in ice volume, climate, and ocean-circulation patterns during glacialinterglacial transitions.

Coastal protection design heights typically consider the superimposed effects of tides, surges, waves, and relative sea-levelrise (SLR), neglecting non-linear feedbacks between these forcing factors. Here, we use hydrodynamic modelling and multivariate statistics to show that shallow coastal areas are extremely sensitive to changing non-linear interactions between individual components caused by SLR. As sea-level increases, the depth-limitation of waves relaxes, resulting in waves with larger periods, greater amplitudes, and higher run-up; moreover, depth and frictional changes affect tide, surge, and wave characteristics, altering the relative importance of other risk factors. Consequently, sea-level driven changes in wave characteristics, and to a lesser extent, tides, amplify the resulting design heights by an average of 48-56%, relative to design changes caused by SLR alone. Since many of the world's most vulnerable coastlines are impacted by depth-limited waves, our results suggest that the overall influence of SLR may be greatly underestimated in many regions.

The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6–8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz-Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sealevelrise during this event. Sealevel rose ∼14 m between 9.5 to 7.5 ka, a pattern consistent with coral records and the ICE-5G glacio-isostatic adjustment model. There were two distinct periods at ∼8.9–8.8 and ∼8.2–7.6 ka when Chesapeake marshes were drown as sealevel rose rapidly at least ∼12 mm yr−1. The latter event occurred after the 8.6–8.2 ka cooling event, coincided with extreme warming and vigorous AMOC centered on 7.9 ka, and may have been due to Antarctic Ice Sheet decay.

The future ice dynamical contribution to sealevelrise (SLR) from 199 ice shelf nourishing drainage basins of the Antarctic Peninsula Ice Sheet is simulated, using the British Antarctic Survey Antarctic Peninsula Ice Sheet Model. Simulations of the grounded ice sheet include response to ice shelf collapse, estimated by tracking thermal ice shelf viability limits in 14 Intergovernmental Panel on Climate Change global climate models ensemble temperature projections. Grounding line retreat in response to ice shelf collapse is parameterized with a new multivariate linear regression model utilizing a range of glaciological and geometric predictor variables. Multimodel means project SLR up to 9.4 mm sealevel equivalent (SLE) by 2200, and up to 19 mm SLE by 2300. Rates of SLR from individual drainage basins throughout the peninsula are similar to 2100, yet diverge between 2100 and 2300 due to individual basin characteristics. Major contributors to SLR are the outlet glaciers feeding southern George VI Ice Shelf, accounting for >75% of total SLR in some model runs. Ice sheet thinning induced by ice-shelf removal is large (up to ˜500 m), especially in Palmer Land in the southern Antarctic Peninsula, and may propagate as far as 135 km inland. These results emphasize the importance of the ice dynamical contribution to future sealevel of the APIS on decadal to centennial timescales.

Coastal protection design heights typically consider the superimposed effects of tides, surges, waves, and relative sea-levelrise (SLR), neglecting non-linear feedbacks between these forcing factors. Here, we use hydrodynamic modelling and multivariate statistics to show that shallow coastal areas are extremely sensitive to changing non-linear interactions between individual components caused by SLR. As sea-level increases, the depth-limitation of waves relaxes, resulting in waves with larger periods, greater amplitudes, and higher run-up; moreover, depth and frictional changes affect tide, surge, and wave characteristics, altering the relative importance of other risk factors. Consequently, sea-level driven changes in wave characteristics, and to a lesser extent, tides, amplify the resulting design heights by an average of 48–56%, relative to design changes caused by SLR alone. Since many of the world’s most vulnerable coastlines are impacted by depth-limited waves, our results suggest that the overall influence of SLR may be greatly underestimated in many regions.

Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sealevel has been 6-9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics—including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-levelrise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.

The Bangladesh Delta is located at the confluence of the mega Ganges, Brahmaputra and Meghan Rivers in the Bay of Bengal. It is home to over 160 million people and is one of the most densely populated countries in the world. It is prone to seasonal transboundary monsoonal flooding, potentially aggravated by more frequent and intensified cyclones resulting from anthropogenic climate change. Sealevelrise, along with tectonic, sediment compaction/load and groundwater extraction induced land uplift/subsidence, have significantly exacerbated these risks and Bangladesh's coastal vulnerability. Bangladesh has built 123 coastal embankments or polders since the 1960's, to protect the coastal regions from cyclone/tidal flooding and to reduce salinity incursions. Since then, many coastal polders have suffered severe erosion and anthropogenic damage, and require repairs or rebuilding. However, the physical and anthropogenic processes governing the historic relative sealevelrise and its future projection towards its quantification remain poorly understood or known, and at present not accurate enough or with an adequately fine local spatial scale for practical mitigation of coastal vulnerability or coastal resilience studies. This study reports on our work in progress to use satellite geodetic and remote sensing observations, including satellite radar altimetry/backscatter measurements over land and in coastal oceans, optical/infrared imageries, and SAR backscatter/InSAR data, to study the feasibility of coastal embankment/polder erosion monitoring, quantify seasonal polder water intrusions, observing polder subsidence, and finally, towards the goal of improving the relative sealevelrise hazards assessment at the local scale in coastal Bangladesh.

Three rapid post-glacial sea-levelrises flooded coastlines with large continental shelves. The last of these, shortly before the interglacial optimum c.7,500BP, not only changed coastal Neolithic societies, but may also have stimulated maritime skills. Two Asian examples explore these aspects. First, during the Mid-Holocene, the Arabian Gulf transgressed as far inland as Ur probably laying down Woolley's famous Ur Flood silt layer between 7,000-5,500 BP. Stratigraphy and dating suggests the phase of rapid sealevelrise immediately preceded the start of the 'Ubaid pottery period. Red-slipped Uruk pottery and copper items then appear from about 6,000BP, but above Woolley's silt layer. The Sumerian King Lists also record a major upheaval and dynastic change after 'the Flood'. Second, the final flooding of the Sunda shelf in Southeast Asia was followed by a maritime extension of human occupation from Northern Melanesia south into the Solomon Islands 6,000 years ago. Simultaneously, further west on the north coast of New Guinea, new archaeological assemblages ap- pear beneath a silt layer left by a pro-grading 6,000 year-old inland sea. The presence of arboriculture items such as betel nuts and the contemporary arrival of dogs and pigs in the same region suggests intrusion from Southeast Asia. This supports Solheim's suggestion that rapid sea-levelrise on the eastern edge of the Sunda Shelf stimulated maritime skills and invention in Southeast Asia. This may have provided the initial stimulus to the first maritime expansion that was later to colonise the whole Pacific.

There is a pressing need to assess resilience of coastal ecosystems against sealevelrise. To develop appropriate response strategies against future climate disturbances, it is important to estimate the magnitude of disturbances that these ecosystems can absorb and to better understand their underlying processes. Hammocks (petenes) coastal ecosystems are highly vulnerable to sealevelrise linked to climate change; their vulnerability is mainly due to its close relation with the sea through underground drainage in predominantly karstic soils. Hammocks are biologically important because of their high diversity and restricted distribution. This study proposes a strategy to assess resilience of this coastal ecosystem when high-precision data are scarce. Approaches and methods used to derive ecological resilience maps of hammocks are described and assessed. Resilience models were built by incorporating and weighting appropriate indicators of persistence to assess hammocks resilience against flooding due to climate change at “Los Petenes Biosphere Reserve”, in the Yucatán Peninsula, Mexico. According to the analysis, 25% of the study area is highly resilient (hot spots), whereas 51% has low resilience (cold spots). The most significant hot spot clusters of resilience were located in areas distant to the coastal zone, with indirect tidal influence, and consisted mostly of hammocks surrounded by basin mangrove and floodplain forest. This study revealed that multi-criteria analysis and the use of GIS for qualitative, semi-quantitative and statistical spatial analyses constitute a powerful tool to develop ecological resilience maps of coastal ecosystems that are highly vulnerable to sealevelrise, even when high-precision data are not available. This method can be applied in other sites to help develop resilience analyses and decision-making processes for management and conservation of coastal areas worldwide. PMID:27611802

There is a pressing need to assess resilience of coastal ecosystems against sealevelrise. To develop appropriate response strategies against future climate disturbances, it is important to estimate the magnitude of disturbances that these ecosystems can absorb and to better understand their underlying processes. Hammocks (petenes) coastal ecosystems are highly vulnerable to sealevelrise linked to climate change; their vulnerability is mainly due to its close relation with the sea through underground drainage in predominantly karstic soils. Hammocks are biologically important because of their high diversity and restricted distribution. This study proposes a strategy to assess resilience of this coastal ecosystem when high-precision data are scarce. Approaches and methods used to derive ecological resilience maps of hammocks are described and assessed. Resilience models were built by incorporating and weighting appropriate indicators of persistence to assess hammocks resilience against flooding due to climate change at "Los Petenes Biosphere Reserve", in the Yucatán Peninsula, Mexico. According to the analysis, 25% of the study area is highly resilient (hot spots), whereas 51% has low resilience (cold spots). The most significant hot spot clusters of resilience were located in areas distant to the coastal zone, with indirect tidal influence, and consisted mostly of hammocks surrounded by basin mangrove and floodplain forest. This study revealed that multi-criteria analysis and the use of GIS for qualitative, semi-quantitative and statistical spatial analyses constitute a powerful tool to develop ecological resilience maps of coastal ecosystems that are highly vulnerable to sealevelrise, even when high-precision data are not available. This method can be applied in other sites to help develop resilience analyses and decision-making processes for management and conservation of coastal areas worldwide.

A tide gauge records a combined signal of the vertical change (positive or negative) in the level of both the sea and the land to which the gauge is affixed; or relative sea-level change, which is typically referred to as relative sea-levelrise (RSLR). Complicating this situation, coastal wetlands exhibit dynamic surface elevation change (both positive and negative), as revealed by surface elevation table (SET) measurements, that is not recorded at tide gauges. Because the usefulness of RSLR is in the ability to tie the change in sealevel to the local topography, it is important that RSLR be calculated at a wetland that reflects these local dynamic surface elevation changes in order to better estimate wetland submergence potential. A rationale is described for calculating wetland RSLR (RSLRwet) by subtracting the SET wetland elevation change from the tide gauge RSLR. The calculation is possible because the SET and tide gauge independently measure vertical land motion in different portions of the substrate. For 89 wetlands where RSLRwet was evaluated, wetland elevation change differed significantly from zero for 80 % of them, indicating that RSLRwet at these wetlands differed from the local tide gauge RSLR. When compared to tide gauge RSLR, about 39 % of wetlands experienced an elevation rate surplus and 58 % an elevation rate deficit (i.e., sealevel becoming lower and higher, respectively, relative to the wetland surface). These proportions were consistent across saltmarsh, mangrove, and freshwater wetland types. Comparison of wetland elevation change and RSLR is confounded by high levels of temporal and spatial variability, and would be improved by co-locating tide gauge and SET stations near each other and obtaining long-term records for both.

Coastal cities will face a range of increasingly severe challenges as sealevelrises, and adaptation to future flood risk will require more than structural defences. Many cities will not be able to rely solely on engineering structures for protection and will need to develop a suite of policy responses to increase their resilience to impacts of risingsealevel. Local governments generally maintain day-to-day responsibility and control over the use of the vast majority of property at risk of flooding, and the tools to promote flood risk adaptation are already within the capacity of most cities. Policy tools available to address other land-use problems can be refashioned and used to adapt to sealevelrise. This study reviews approaches for urban adaptation through case studies of cities which have developed flood adaptation strategies that combine structural defences with innovative approaches to living with flood risk. The aim of the overall project is to produce a 'roadmap' to guide practitioners through the process of analysing coastal flood risk in urban areas. Technical knowledge of flood risk reduction measures is complemented with a consideration of the essential impact that local policy has on the treatment of coastal flooding and the constraints and opportunities that result from the specific country or locality characteristics in relation to economic, political, social and environmental priorities, which are likely to dictate the approach to coastal flooding and the actions proposed. Detailed analyses of the adaptation strategies used by Rotterdam (Netherlands), Bristol (UK), and Norfolk (Virginia) are used to draw out a range of good practice elements that promote effective adaptation to sealevelrise. These can be grouped into risk reduction, governance issues, and insurance, and can be used to provide examples of how other cities could adopt and implement flood adaptation strategies from a relatively limited starting position. Most cities will

U.S. Geological Survey (USGS) scientists are developing comprehensive records of historical and modern coral reef growth and calcification rates relative to changing seawater chemistry resulting from increasing atmospheric CO2 from the pre-industrial period to the present. These records will provide the scientific foundation for predicting future impacts of ocean acidification and sea-levelrise on coral reef growth. Changes in coral growth rates in response to past changes in seawater pH are being examined by using cores from coral colonies.

Sealevelrise (SLR) over the 21st century will cause significant redistribution of valuable coastal habitats. Seagrasses form extensive and highly productive meadows in shallow coastal seas support high biodiversity, including economically valuable and threatened species. Predictive habitat models can inform local management actions that will be required to conserve seagrass faced with multiple stressors. We developed novel modelling approaches, based on extensive field data sets, to examine the effects of sealevelrise and other stressors on two representative seagrass habitats in Australia. First, we modelled interactive effects of SLR, water clarity and adjacent land use on estuarine seagrass meadows in Moreton Bay, Southeast Queensland. The extent of suitable seagrass habitat was predicted to decline by 17% by 2100 due to SLR alone, but losses were predicted to be significantly reduced through improvements in water quality (Fig 1a) and by allowing space for seagrass migration with inundation. The rate of sedimentation in seagrass strongly affected the area of suitable habitat for seagrass in sealevelrise scenarios (Fig 1b). Further research to understand spatial, temporal and environmental variability of sediment accretion in seagrass is required. Second, we modelled changes in wave energy distribution due to predicted SLR in a linked coral reef and seagrass ecosystem at Lizard Island, Great Barrier Reef. Scenarios where the water depth over the coral reef deepened due to SLR and minimal reef accretion, resulted in larger waves propagating shoreward, changing the existing hydrodynamic conditions sufficiently to reduce area of suitable habitat for seagrass. In a scenario where accretion of the coral reef was severely compromised (e.g. warming, acidification, overfishing), the probability of the presence of seagrass declined significantly. Management to maintain coral health will therefore also benefit seagrasses subject to SLR in reef environments. Further

Policy makers and stakeholders in the coastal zone are equally challenged by the risk of an anticipated rise of coastal Local SeaLevel (LSL) as a consequence of future global warming. Many low-lying and often densely populated coastal areas are under risk of increased inundation. More than 40% of the global population is living in or near the coastal zone and this fraction is steadily increasing. A rise in LSL will increase the vulnerability of coastal infrastructure and population dramatically, with potentially devastating consequences for the global economy, society, and environment. Policy makers are faced with a trade-off between imposing today the often very high costs of coastal protection and adaptation upon national economies and leaving the costs of potential major disasters to future generations. They are in need of actionable information that provides guidance for the development of coastal zones resilient to future sealevel changes. Part of this actionable information comes from risk and vulnerability assessments, which require information on future LSL changes as input. In most cases, a deterministic approach has been applied based on predictions of the plausible range of future LSL trajectories as input. However, there is little consensus in the scientific community on how these trajectories should be determined, and what the boundaries of the plausible range are. Over the last few years, many publications in Science, Nature and other peer-reviewed scientific journals have revealed a broad range of possible futures and significant epistemic uncertainties and gaps concerning LSL changes. Based on the somewhat diffuse science input, policy and decision makers have made rather different choices for mitigation and adaptation in cases such as Venice, The Netherlands, New York City, and the San Francisco Bay area. Replacing the deterministic, prediction-based approach with a statistical one that fully accounts for the uncertainties and epistemic gaps

Global sea-levelrise rates have increased over the last century, with dramatic rate increases expected over the coming century and beyond. Not only are rates projected to approach those of the previous deglaciation, the actual increase in elevation by the end of the century (potentially 1m or more) will be significant in terms of the elevations of low-lying coastal landforms. Coral reef islands, often called 'cays' or 'motus', which generally comprise the subaerial portion of atolls, are particularly sensitive to sea-levelrise. These landforms are typically low-lying (on the order of meters high), and are formed of wave-transported detrital sediment perched atop coralline rock. As opposed to barrier islands that can be supplied by offshore sediment from the shoreface, breakdown of corals and the shallow offshore lithology can serve as a source of sediment to reef islands, which can help build these islands as sealevelrises. Here, we present a morphodynamic model to explore the combined effects of sea-levelrise, sediment supply, and overwash processes on the evolution of reef islands. Model results demonstrate how reef islands are particularly sensitive to the offshore generation of sediment. When this onshore sediment supply is low, islands migrate lagoonward via storm overwash, Islands migrate over the proximal lagoonward regions, which tend to include a shallow (~2m) platform, until they reach the edge of a typically very deep lagoon (up to 60m or more). At the lagoon edge, reef islands stop their migration and eventually drown overwash sediment flux is lost to the lagoon. In contrast, a high sediment supply of offshore sediment can bulwark reef islands before reaching the lagoon edge. One possibility is that the island attains a ';static equilibrium' in which the overwash flux fills the top-barrier accommodation created by sea-levelrise, and the island surface area is maintained. When the sediment supply is very high, however, the island can undergo rapid

Sealevel has risen approximately 1.2 mm/year over the last 100 years (Hennessy et al. 2004) and is predicted to rise up to 80 cm by 2100 relative to 1990 sealevels (IPCC 2007). The number of extreme events related to sealevel such as higher sealevels and increased inter-annual variability have also increased in frequency in the same time period (Hennessy et al. 2004). Globally, large areas of coastal and estuarine floodplains are underlain by sulfidic sediments and acid sulfate soils (ASS). These sediments frequently contain high concentrations of acidity and trace metals. A significant portion of the stored acidity occurs in the form of exchangeable and hydrolysable acidic metal cations such as Al and Fe. Watertables in these environments are often close to the surface and intercepted by relatively shallow drains. Due to their low elevation and locations, these floodplains are highly susceptible to pulses of saline water caused by saltwater intrusion, storm surge and risingsealevels. Construction of extensive drainage systems has further increased the susceptibility of the floodplain to seawater inundation by increasing connectivity to the estuarine channel. This risk is likely to increase in the future with predicted increases in sealevel and extreme events due to climate change. This study uses both batch experiments to determine the effects of increasing ionic strength on exchange processes and trace metal desorption in oxidised floodplain sediments and sulfidic drain sediments, and intact soil cores to determine the surface water-porewater interactions over the short term following seawater inundation in coastal floodplain sediments. We found that that saline inundation of oxidised ASS floodplain sediments, even by relatively brackish water may cause rapid, shorter-term water quality changes and a pulse release of acidity due to desorption of acidic metal cations (Wong et al. 2010). We also found that trace metals can be mobilised from sulfidic

Species face many threats, including accelerated climate change, sealevelrise, and conversion and degradation of habitat from human land uses. Vulnerability assessments and prioritization protocols have been proposed to assess these threats, often in combination with information such as species rarity; ecological, evolutionary or economic value; and likelihood of success. Nevertheless, few vulnerability assessments or prioritization protocols simultaneously account for multiple threats or conservation values. We applied a novel vulnerability assessment tool, the Standardized Index of Vulnerability and Value, to assess the conservation priority of 300 species of plants and animals in Florida given projections of climate change, human land-use patterns, and sealevelrise by the year 2100. We account for multiple sources of uncertainty and prioritize species under five different systems of value, ranging from a primary emphasis on vulnerability to threats to an emphasis on metrics of conservation value such as phylogenetic distinctiveness. Our results reveal remarkable consistency in the prioritization of species across different conservation value systems. Species of high priority include the Miami blue butterfly (Cyclargus thomasi bethunebakeri), Key tree cactus (Pilosocereus robinii), Florida duskywing butterfly (Ephyriades brunnea floridensis), and Key deer (Odocoileus virginianus clavium). We also identify sources of uncertainty and the types of life history information consistently missing across taxonomic groups. This study characterizes the vulnerabilities to major threats of a broad swath of Florida's biodiversity and provides a system for prioritizing conservation efforts that is quantitative, flexible, and free from hidden value judgments.

Species face many threats, including accelerated climate change, sealevelrise, and conversion and degradation of habitat from human land uses. Vulnerability assessments and prioritization protocols have been proposed to assess these threats, often in combination with information such as species rarity; ecological, evolutionary or economic value; and likelihood of success. Nevertheless, few vulnerability assessments or prioritization protocols simultaneously account for multiple threats or conservation values. We applied a novel vulnerability assessment tool, the Standardized Index of Vulnerability and Value, to assess the conservation priority of 300 species of plants and animals in Florida given projections of climate change, human land-use patterns, and sealevelrise by the year 2100. We account for multiple sources of uncertainty and prioritize species under five different systems of value, ranging from a primary emphasis on vulnerability to threats to an emphasis on metrics of conservation value such as phylogenetic distinctiveness. Our results reveal remarkable consistency in the prioritization of species across different conservation value systems. Species of high priority include the Miami blue butterfly (Cyclargus thomasi bethunebakeri), Key tree cactus (Pilosocereus robinii), Florida duskywing butterfly (Ephyriades brunnea floridensis), and Key deer (Odocoileus virginianus clavium). We also identify sources of uncertainty and the types of life history information consistently missing across taxonomic groups. This study characterizes the vulnerabilities to major threats of a broad swath of Florida’s biodiversity and provides a system for prioritizing conservation efforts that is quantitative, flexible, and free from hidden value judgments. PMID:24260447

Extreme sealevels due to storm surge and future sealevelrise (SLR) in the year 2050 are estimated using ensemble empirical mode decomposition (EEMD) and extreme value analysis (EVA) based on long-term sealevel records from Hiron Point (HP) on the coast of western Bangladesh. EEMD is an adaptive method that can detrend the nonlinear trend and separate the tidal motions from the original sealevel records to reconstruct storm surge levels at HP. The reconstructed storm surge levels are then applied to EVA to obtain the extreme storm surges in the target return periods at a 95% confidence interval (CI). The 30, 50, and 100 year return levels at HP obtained by EVA are 1.59, 1.66, and 1.75 m. The SLR trend obtained from EEMD is 4.46 mm/yr over April 1990 to March 2009, which is larger than the recent altimetry-based global rate of 3.3 ± 0.4 mm/yr over the period from 1993 to 2007. The resulting SLR in 2050 is estimated as 0.34 m. Therefore, the extreme sealevel in 2050 due to SLR and the storm surge at a 100 year return level would be 2.09 m (95% CI from 1.91 to 2.48 m). The SLR depends not only on changes in the mass and volume of sea water but also on other factors, such as local subsidence, river discharge, sediment and the effects of vegetation. The residual nonlinear trend of SLR obtained from EEMD can be regarded as an adaptive sealevel after considering those factors and their nonlinearity.

The coastal and estuarine storm tide model (CEST) was employed to estimate storm surges and associated flood caused by Hurricane Andrew for scenarios of sealevelrise (SLR) from 0.15 to 1.05 m with an interval of 0.15 m. The interaction between storm surges and SLR is almost linear at the open Atlantic Ocean outside Biscayne Bay, with slight reduction in peak storm surge heights as sealevelrises. The nonlinear interaction between storm surges and SLR is weak in Biscayne Bay, leading to small differences (-0.2-0.2 m) in peak storm surge heights estimated using CEST and the linear superposition methods. Therefore, it is appropriate to estimate elevated storm surges caused by SLR in these areas by adding the SLR magnitude to storm surge heights. However, the magnitude and extent of inundation at the mainland area by Biscayne Bay estimated by numerical simulations are, respectively, 16-30% and 22-24% larger on average than those generated by the linear superposition of storm surges and SLR, indicating a strong nonlinear interaction between storm surges and SLR. The population and property affected by the storm surge inundation estimated by numerical simulations differ up to 50-140% from that estimated by the linear superposition methods. Therefore, it is inappropriate to estimate the exacerbated magnitude and extent of storm surge flooding by SLR and affected population and property using the linear superpostion methods. The strong nonlinear interaction between surge flooding and SLR at a specific location occurs at the initial stage of SLR when the water depth under an elevated sealevel is less than 0.7 m, while the interaction becomes linear as the depth exceeds 0.7 m.

Ningaloo Reef, located along the northwest coast of Australia, is one of the longest fringing coral reefs in the world extending ~300 km. Similar to other fringing reefs, it consists of a barrier reef ~1-6 km offshore with occasional gaps, backed by a shallow lagoon. Wave breaking on the reef generates radiation stress gradients that produces wave setup across the reef and lagoon and mean currents across the reef. A section of Ningaloo Reef at Sandy Bay was chosen as the focus of an intense 6-week field experiment and numerical simulation using the wave model SWAN coupled to the three-dimensional circulation model ROMS. The physics of nearshore processes such as wave breaking, wave setup and mean flow across the reef was investigated in detail by examining the various momentum balances established in the system. The magnitude of the terms and the distance of their peaks from reef edge in the momentum balance were sensitive to the changes in mean sealevel, e.g. the wave forces decreased as the mean water depth increased (and hence, wave breaking dissipation was reduced). This led to an increase in the wave power at the shoreline, a slight shift of the surf zone to the lee side of the reef and changes in the intensity of the circulation. The predicted hydrodynamic fields were input into a Lagrangian particle tracking model to estimate the transport time scale of the reef-lagoon system. Flushing time of the lagoon with the open ocean was computed using two definitions in renewal of semi-enclosed water basins and revealed the sensitivity of such a transport time scale to methods. An increase in the lagoon exchange rate at smaller mean sea-levelrise and the decrease at higher mean sea-levelrise was predicted through flushing time computed using both methods.

Surface melt on the Greenland ice sheet has shown increasing trends in areal extent and duration since the beginning of the satellite era. Records for melt were broken in 2005, 2007, 2010 and 2012. Much of the increased surface melt is occurring in the percolation zone, a region of the accumulation area that is perennially covered by snow and firn (partly compacted snow). The fate of melt water in the percolation zone is poorly constrained: some may travel away from its point of origin and eventually influence the ice sheet's flow dynamics and mass balance and the global sealevel, whereas some may simply infiltrate into cold snow or firn and refreeze with none of these effects. Here we quantify the existing water storage capacity of the percolation zone of the Greenland ice sheet and show the potential for hundreds of gigatonnes of meltwater storage. We collected in situ observations of firn structure and meltwater retention along a roughly 85-kilometre-long transect of the melting accumulation area. Our data show that repeated infiltration events in which melt water penetrates deeply (more than 10 metres) eventually fill all pore space with water. As future surface melt intensifies under Arctic warming, a fraction of melt water that would otherwise contribute to sea-levelrise will fill existing pore space of the percolation zone. We estimate the lower and upper bounds of this storage sink to be 322 ± 44 gigatonnes and 1,289(+388)(-252) gigatonnes, respectively. Furthermore, we find that decades are required to fill this pore space under a range of plausible future climate conditions. Hence, routing of surface melt water into filling the pore space of the firn column will delay expansion of the area contributing to sea-levelrise, although once the pore space is filled it cannot quickly be regenerated.

The “Sea‐Level Affecting Marshes Model” (SLAMM) is a moderate resolution model used to predict the effects of sealevelrise on marsh habitats (Craft et al. 2009). SLAMM has been used extensively on both the west coast (e.g., Glick et al., 2007) and east coast (e.g., Geselbracht et al., 2011) of the United States to evaluate potential changes in the distribution and extent of tidal marsh habitats. However, a limitation of the current version of SLAMM, (Version 6.2) is that it lacks the ability to model distribution changes in seagrass habitat resulting from sealevelrise. Because of the ecological importance of SAV habitats, U.S. EPA, USGS, and USDA partnered with Warren Pinnacle Consulting to enhance the SLAMM modeling software to include new functionality in order to predict changes in Zostera marina distribution within Pacific Northwest estuaries in response to sealevelrise. Specifically, the objective was to develop a SAV model that used generally available GIS data and parameters that were predictive and that could be customized for other estuaries that have GIS layers of existing SAV distribution. This report describes the procedure used to develop the SAV model for the Yaquina Bay Estuary, Oregon, appends a statistical script based on the open source R software to generate a similar SAV model for other estuaries that have data layers of existing SAV, and describes how to incorporate the model coefficients from the site‐specific SAV model into SLAMM to predict the effects of sealevelrise on Zostera marina distributions. To demonstrate the applicability of the R tools, we utilize them to develop model coefficients for Willapa Bay, Washington using site‐specific SAV data.

How might climate change and the resulting sealevelrise (SLR) affect coastal facilities? The changing frequency of nuisance flooding events will likely lead to increases in costs and may require changes to the management of assets. While a significant literature exists for climate change and extreme event impacts, there is a gap in the literature for impacts from nuisance events. This presentation explores methods for analyzing the changing frequency and spatial distribution of flooding events through a case study at the United States Naval Academy located in Annapolis, Maryland. We show that `nuisance events' -- not infrequent but low impact events, will become more frequent as a result of climate change and the resultant sealevelrise. An increase in nuisance flooding events could lead to negative effects on day-to-day operations. For example, a vulnerable building on the campus currently averages 0.25 flood events per year at a cost of between 2,500 - 3,700 USD (deployment of flood protection measures). By 2055 the same building in an average year would need to deploy flood protection measures 33 times at a cost of between 300,000 - 500,000 USD (assuming constant costs). The costs for the entire installation could be much higher given the number of buildings located in vulnerable areas, in addition to the risk adverse nature of operations managers. This case study identifies a need to better understand the local relationship between operations costs, thresholds, and changes in locally important climate variables.

Extreme weather, sea-levelrise and degraded coastal ecosystems are placing people and property at greater risk of damage from coastal hazards. The likelihood and magnitude of losses may be reduced by intact reefs and coastal vegetation, especially when those habitats fringe vulnerable communities and infrastructure. Using five sea-level-rise scenarios, we calculate a hazard index for every 1km2 of the United States coastline. We use this index to identify the most vulnerable people and property as indicated by being in the upper quartile of hazard for the nation's coastline. The number of people, poor families, elderly and total value of residential property that are most exposed to hazards can be reduced by half if existing coastal habitats remain fully intact. Coastal habitats defend the greatest number of people and total property value in Florida, New York and California. Our analyses deliver the first national map of risk reduction owing to natural habitats and indicates where conservation and restoration of reefs and vegetation have the greatest potential to protect coastal communities.

The rate of global sea-levelrise (SLR) has been increasing over the past century, primarily due to global warming and associated melting of polar icecaps. Recent projections indicate that sealevel could rise globally by more than 1 m by 2100. Potential impacts of SLR in coastal regions are a concern, especially in California which has a ~1,800 km long coastline and where >70% of the population live in coastal counties. However, information on potential impacts of SLR-driven groundwater inundation in California is limited. In this study, we examined potential impacts of SLR-driven groundwater inundation in select low-lying areas of California, including Arcata, Stinson Beach, and Malibu Lagoon, under +1 m and +2 m SLR scenarios. The results indicate that Arcata, Stinson Beach, and Malibu Lagoon will be impacted by SLR-driven inundation to different extents. For example, ~15% of present-day dry land in Malibu Lagoon will be inundated with groundwater and the lagoon will be expanded by >100% relative to present-day area under the +2 m SLR scenario. In addition, the area with shallow water table ≤2 m from the ground surface will increase substantially with SLR at Malibu Lagoon. SLR-driven groundwater inundation could be problematic in some low-lying coastal regions. Therefore, improved understanding of potential response of coastal aquifers to SLR could help in preparing for mitigation and adaptation.

Few studies have empirically examined the suite of mechanisms that underlie the distributional shifts displayed by organisms in response to changing climatic condition. Mangrove forests are expected to move inland as sea-levelrises, encroaching on saltmarsh plants inhabiting higher elevations. Mangrove propagules are transported by tidal waters and propagule dispersal is likely modified upon encountering the mangrove-saltmarsh ecotone, the implications of which are poorly known. Here, using an experimental approach, we record landward and seaward dispersal and subsequent establishment of mangrove propagules that encounter biotic boundaries composed of two types of saltmarsh taxa: succulents and grasses. Our findings revealed that propagules emplaced within saltmarsh vegetation immediately landward of the extant mangrove fringe boundary frequently dispersed in the seaward direction. However, propagules moved seaward less frequently and over shorter distances upon encountering boundaries composed of saltmarsh grasses versus succulents. We uniquely confirmed that the small subset of propagules dispersing landward displayed proportionately higher establishment success than those transported seaward. Although impacts of ecotones on plant dispersal have rarely been investigated in situ, our experimental results indicate that the interplay between tidal transport and physical attributes of saltmarsh vegetation influence boundary permeability to propagules, thereby directing the initial phase of shifting mangrove distributions. The incorporation of tidal inundation information and detailed data on landscape features, such as the structure of saltmarsh vegetation at mangrove boundaries, should improve the accuracy of models that are being developed to forecast mangrove distributional shifts in response to sea-levelrise. PMID:25760867

Coastal communities in portions of the United States are vulnerable to storm-surge inundation from hurricanes and this vulnerability will likely increase, given predicted rises in sealevel from climate change and growing coastal development. In this paper, we provide an overview of research to determine current and future societal vulnerability to hurricane storm-surge inundation and to help public officials and planners integrate these scenarios into their long-range land use plans. Our case study is Sarasota County, Florida, where planners face the challenge of balancing increasing population growth and development with the desire to lower vulnerability to storm surge. Initial results indicate that a large proportion of Sarasota County's residential and employee populations are in areas prone to storm-surge inundation from a Category 5 hurricane. This hazard zone increases when accounting for potential sea-level-rise scenarios, thereby putting additional populations at risk. Subsequent project phases involve the development of future land use and vulnerability scenarios in collaboration with local officials. Copyright ASCE 2008.

We have used airborne laser altimetry to estimate volume changes of 67 glaciers in Alaska from the mid-1950s to the mid-1990s. The average rate of thickness change of these glaciers was -0.52 m/year. Extrapolation to all glaciers in Alaska yields an estimated total annual volume change of -52 +/- 15 km3/year (water equivalent), equivalent to a rise in sealevel (SLE) of 0.14 +/- 0.04 mm/year. Repeat measurements of 28 glaciers from the mid-1990s to 2000-2001 suggest an increased average rate of thinning, -1.8 m/year. This leads to an extrapolated annual volume loss from Alaska glaciers equal to -96 +/- 35 km3/year, or 0.27 +/- 0.10 mm/year SLE, during the past decade. These recent losses are nearly double the estimated annual loss from the entire Greenland Ice Sheet during the same time period and are much higher than previously published loss estimates for Alaska glaciers. They form the largest glaciological contribution to risingsealevel yet measured.

The impact of elevated storm surge on a barrier island tends to be considered from a single cross-shore dimension and dependent only on the relative elevations of the storm surge and dune. However, the foredune line is rarely uniform and can exhibit considerable variation in height and width alongshore at a range of length scales ranging from tens of meters to several kilometers. LiDAR data from Santa Rosa Island in northwest Florida, Padre Island, Texas and Assateague Island, Maryland are used to explore how the dune morphology varies alongshore and how this variability is altered by storms and post-storm recovery. While the alongshore variation in dune height can be approximated by a power law, there are scale-dependent variations in the dune that exhibit different responses to storm erosion and post-storm recovery. This suggests that the alongshore variation in dune morphology reflects the history of storm impact and recovery, and that changes in the variance magnitude through time may provide insight into whether the island will be resilient as it transgresses with risingsealevel. The difference in variance magnitude at large spatial scales is associated with the framework geology unique to each island and a dominant control on island response to sealevelrise.

The Third National Climate Assessment addressed sealevelrise and aggravated coastal flood exposure in all regions, but was completed before high quality lidar-based elevation data became available throughout the entire coastal United States (excluding Alaska). Here we present what we believe to be the first full national assessment incorporating these data. The assessment includes tabulation of land less than 1-6 m above the local high tide line, and of a wide range of features sitting on that land, including total population, socially vulnerable population, housing, property value, road miles, power plants, schools, hospitals, and a wide range of other infrastructure and critical facilities, as well as EPA-listed facilities that are potential sources of contamination during floods or permanent inundation. Tabulations span from zip code to national levels. Notable patterns include the strong concentration of exposure across multiple scales, with a small number of states accounting for most of the total national exposure; and a small number of zip codes accounting for a large proportion of the exposure within many states. Additionally, different features show different exposure patterns; in one example, land and road miles have relatively high exposure but population and property have relatively low exposure in North Carolina. The assessment further places this exposure analysis in the context of localized sealevelrise projections integrated with coastal flood risk.

Over the past 50 years, retreating glaciers and ice caps contributed 0.5mmyr-1 to sea-levelrise, and one third of this contribution is believed to come from ice masses bordering the Gulf of Alaska. However, these estimates of ice loss in Alaska are based on measurements of a limited number of glaciers that are extrapolated to constrain ice wastage in the many thousands of others. Uncertainties in these estimates arise, for example, from the complex pattern of decadal elevation changes at the scale of individual glaciers and mountain ranges. Here we combine a comprehensive glacier inventory with elevation changes derived from sequential digital elevation models. We find that between 1962 and 2006, Alaskan glaciers lost 41.9+/-8.6km3yr-1 of water, and contributed 0.12+/-0.02mm yr-1 to sea-levelrise, 34% less than estimated earlier. Reasons for our lower values include the higher spatial resolution of our glacier inventory as well as the reduction of ice thinning underneath debris and at the glacier margins, which were not resolved in earlier work. We suggest that estimates of mass loss from glaciers and ice caps in other mountain regions could be subject to similar revisions.

Few studies have empirically examined the suite of mechanisms that underlie the distributional shifts displayed by organisms in response to changing climatic condition. Mangrove forests are expected to move inland as sea-levelrises, encroaching on saltmarsh plants inhabiting higher elevations. Mangrove propagules are transported by tidal waters and propagule dispersal is likely modified upon encountering the mangrove-saltmarsh ecotone, the implications of which are poorly known. Here, using an experimental approach, we record landward and seaward dispersal and subsequent establishment of mangrove propagules that encounter biotic boundaries composed of two types of saltmarsh taxa: succulents and grasses. Our findings revealed that propagules emplaced within saltmarsh vegetation immediately landward of the extant mangrove fringe boundary frequently dispersed in the seaward direction. However, propagules moved seaward less frequently and over shorter distances upon encountering boundaries composed of saltmarsh grasses versus succulents. We uniquely confirmed that the small subset of propagules dispersing landward displayed proportionately higher establishment success than those transported seaward. Although impacts of ecotones on plant dispersal have rarely been investigated in situ, our experimental results indicate that the interplay between tidal transport and physical attributes of saltmarsh vegetation influence boundary permeability to propagules, thereby directing the initial phase of shifting mangrove distributions. The incorporation of tidal inundation information and detailed data on landscape features, such as the structure of saltmarsh vegetation at mangrove boundaries, should improve the accuracy of models that are being developed to forecast mangrove distributional shifts in response to sea-levelrise.

Coral reef islands have a self-sustaining mechanism that expands and maintains the islands through the deposition of calcium carbonate (CaCO3) by marine organisms. However, the human societies established on such low-lying coral reef islands are vulnerable to rapid sea-levelrises. Enhancing the self-sustaining mechanism of coral reefs will become one of the required sustainable countermeasures against sea-levelrise. We examined the feasibility of mass culturing the large benthic foraminifera Baculogypsina sphaerulata, which is known as "living sand." We developed a rearing system with the key components of an artificial lawn as a habitat and a stirring device to create vertical water currents. Batches of B. sphaerulata in two different size groups were reared to examine size growth and reproduction under the culture conditions. All culture batches reproduced asexually following generations over 6 months in culture. The small-sized group exhibited steady growth, whereas the large-sized group underwent a reduction in mean size because large individuals (> 1.5 mm2) died off. Similar traits of size structure between the culture batches and natural populations indicate that our culturing conditions can successfully reproduce environments similar to the habitat of this species. Reproduction, consistent size growth, and size structure similar to the natural population indicate that the examined rearing system is viable for culturing Foraminifera at a large scale.

Contemporary sea-levelrise will inundate coastal habitats with seawater more frequently, disrupting the life cycles of terrestrial fauna well before permanent habitat loss occurs. Sea turtles are reliant on low-lying coastal habitats worldwide for nesting, where eggs buried in the sand remain vulnerable to inundation until hatching. We show that saltwater inundation directly lowers the viability of green turtle eggs (Chelonia mydas) collected from the world's largest green turtle nesting rookery at Raine Island, Australia, which is undergoing enigmatic decline. Inundation for 1 or 3 h reduced egg viability by less than 10%, whereas inundation for 6 h reduced viability by approximately 30%. All embryonic developmental stages were vulnerable to mortality from saltwater inundation. Although the hatchlings that emerged from inundated eggs displayed normal physical and behavioural traits, hypoxia during incubation could influence other aspects of the physiology or behaviour of developing embryos, such as learning or spatial orientation. Saltwater inundation can directly lower hatching success, but it does not completely explain the consistently low rates of hatchling production observed on Raine Island. More frequent nest inundation associated with sea-levelrise will increase variability in sea turtle hatching success spatially and temporally, due to direct and indirect impacts of saltwater inundation on developing embryos.

Climate has captured the attention of the public but its complexity can cause interested individuals to turn to opinion pieces, news articles or blogs for information. These platforms often oversimplify or present heavily interpreted or personalized perspectives. Data interactives are an extremely effective way to explore complex geoscience topics like climate, opening windows of understanding for the user that have previously been closed. Layering data onto maps through programs like GeoMapApp and the Earth Observer App has allowed users to dig directly into science data, but with only limited scaffolding. The interactive 'Polar Explorer: SeaLevel Explorer App' provides a richly layered introduction to a range of topics connected to sealevelrise. Each map is supported with a pop up and a short audio file of supplementary material, and an information page that includes the data source and links for further reading. This type of learning platform works well for both the formal and informal learning environment. Through science data displayed as map visualizations the user is invited into topics through an introductory question, such as "Why does sealevel change?" After clicking on that question the user moves to a second layer of questions exploring the role of the ocean, the atmosphere, the contribution from the world's glaciers, world's ice sheets and other less obvious considerations such as the role of post-glacial rebound, or the mining of groundwater. Each question ends in a data map, or series of maps, that offer opportunities to interact with the topic. Under the role of the ocean 'Internal Ocean Temperature' offers the user a chance to touch to see temperature values spatially over the world's ocean, or to click through a data series starting at the ocean surface and diving to 5000 meters of depth showing how temperature changes with depth. Other sections, like the role of deglaciation of North America, allow the user to click and see change through

Coastal cities will face a range of increasingly severe challenges as sealevelrises, and adaptation to future flood risk will require more than structural defences. Many cities will not be able to rely solely on engineering structures for protection and will need to develop a suite of policy responses to increase their resilience to impacts of risingsealevel. The tools to promote flood risk adaptation are already within the capacity of most cities, with an assortment of policy tools available to address other land-use problems which can be refashioned and used to adapt to sealevelrise. This study reviews approaches for urban adaptation through detailed analyses of case studies of cities which have developed flood adaptation strategies that combine structural defences with innovative approaches to living with flood risk. The aim of the overall project is to produce a 'roadmap' to guide practitioners through the process of analysing coastal flood risk in urban areas. Methodologies and tools to estimate vulnerability to coastal flooding, damages suffered, and the assessment of flood defences and adaptation measures are complemented with a discussion on the essential impact that local policy has on the treatment of coastal flooding and the constraints and opportunities that result from the specific country or locality characteristics in relation to economic, political, social and environmental priorities, which are likely to dictate the approach to coastal flooding and the actions proposed. Case studies of adaptation strategies used by Rotterdam, Bristol, Ho Chi Minh City and Norfolk, Virginia, are used to draw out a range of good practice elements that promote effective adaptation to sealevelrise. These can be grouped into risk reduction, governance issues, and insurance, and can be used to provide examples of how other cities could adopt and implement flood adaptation strategies from a relatively limited starting position. Most cities will neither be able to

There is deliberate attention being paid to studying sea-levelrise impacts on the lower St. Johns River, a drowned coastal plain-type estuary with low topographic drive, located in northeastern Florida. One area of attention is salinity in the river, which influences the entire food web, including sea and marsh grasses, juvenile crustaceans and fishes, wading birds and migratory waterfowl, marine mammals and other predator animals. It is expected that elevated ocean levels will increase the salinity of the estuarine waters, leading to deleterious effects on dependent species of the river biology. The objective of the modeling and analysis was: 1) to establish baseline conditions of salinity for the lower St. Johns River; and 2) to examine future conditions of salinity, as impacted by sea-levelrise. Establishing baseline conditions entailed validation of the model for present-day salinity in the lower St. Johns River via comparison to available data. Examining future conditions entailed application of the model for sea-levelrise scenarios, with comparison to the baseline conditions, for evaluation of sea-levelrise impacts on salinity. While the central focus was on the physics of sea-levelrise impacts on salinity, some level of salinity-biological assessment was conducted to identify sea-levelrise/salinity thresholds, as related to negatively impacting different species of the river biology.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise within Kaloko-Honokohau National Historical Park in Hawaii. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined, and an index value calculated for 500-meter grid cells covering the park. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-levelrise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Kaloko-Honokohau National Historical Park consists of carbonate sand beaches, coral rubble, rocky shoreline, and mangrove wetland areas. The areas within Kaloko-Honokohau National Historical Park that are likely to be most vulnerable to sea-levelrise based on this analysis are areas of unconsolidated sediment and highest wave energy.

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-levelrise along the Northern Gulf of Mexico from Galveston, TX, to Panama City, FL. The CVI ranks the following in terms of their physical contribution to sea-levelrise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-levelrise, historical shoreline change rate, mean tidal range, and mean significant wave height. The rankings for each variable are combined and an index value is calculated for 1-kilometer grid cells along the coast. The CVI highlights those regions where the physical effects of sea-levelrise might be the greatest. The CVI assessment presented here builds on an earlier assessment conducted for the Gulf of Mexico. Recent higher resolution shoreline change, land loss, elevation, and subsidence data provide the foundation for a better assessment for the Northern Gulf of Mexico. The areas along the Northern Gulf of Mexico that are likely to be most vulnerable to sea-levelrise are parts of the Louisiana Chenier Plain, Teche-Vermillion Basin, and the Mississippi barrier islands, as well as most of the Terrebonne and Barataria Bay region and the Chandeleur Islands. These very high vulnerability areas have the highest rates of relative sea-levelrise and the highest rates of shoreline change or land area loss. The information provided by coastal vulnerability assessments can be used in long-term coastal management and policy decision making.

The Greenland Ice Sheet (GIS) is an important contributor to present-day sealevelrise, and the ice sheet's importance for sealevelrise will likely increase with Arctic temperatures. Some scientists have recently suggested that geoengineering, the deliberate management of Earth's climate, could prevent sealevelrise from the ice sheets. Previous efforts to assess geoengineering's effects on the GIS and sealevelrise have broken important new ground, but neglect key feedbacks and/or are silent on the short-term effects of geoengineering that are perhaps most important for decision-making. Here, we use a simplified, three-dimensional model of the GIS (SICOPOLIS by Ralf Greve) to examine the response of the Greenland Ice Sheet under plausible geoengineering scenarios. We find that i) the GIS generally continues to melt over the first 100 yr after geoengineering initiation; ii) reductions in GIS sealevel contributions over these first 100 yr are small; and iii) there is a delay of decades to centuries between the initiation of aggressive geoengineering and any regrowth of the ice sheet, and the rate of this regrowth is slow. However, geoengineering produces appreciable reductions in the rate of sealevelrise contributions from the GIS within the first few decades. Our results suggest that past studies have overestimated the effectiveness of geoengineering in preventing mass loss from the Greenland Ice Sheet and in reversing sealevelrise once it has occurred. We comment on the importance of feedbacks in the ice sheet system in assessing geoengineering's effectiveness in reducing sealevelrise from the GIS.

Published values for the long-term, global mean sealevelrise determined from tide gauge records range from about one to three mm per year. The scatter of the estimates appears to arise largely from the use of data from gauges located at convergent tectonic plate boundaries where changes of land elevation give fictitious sealevel trends, and the effects of large interdecadal and longer sealevel variations on short (less than 50+ years) or sappy records. In addition, virtually all gauges undergo subsidence or uplift due to isostatic rebound from the last deglaciation at a rate comparable to or greater than the secular rise of sealevel. Modeling rebound by the ICE-3G model of Tushingham and Peltier (1990) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sealevel records. A global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 yields the global sealevelrise value 1.8 mm/year +/- 0.1. Greenhouse warming scenarios commonly forecast an additional acceleration of global sealevel in the next 5 or 6+ decades in the range 0.1-0.2 mm/yr2. Because of the large power at low frequencies in the sealevel spectrum, very long tide gauge records (75 years minimum) have been examined for past apparent sealevelacceleration. For the 80-year period 1905-1985, 23 essentially complete tide gauge records in 10 geographic groups are available for analysis. These yielded the apparent global acceleration -0.011 (+/- 0.012) mm/yr2. A larger, less uniform set of 37 records in the same 10 groups with 92 years average length covering the 141 years from 1850-1991 gave 0.001 (+/- 0.008) mm/yr2. Thus there is no evidence for an apparent acceleration in the past 100+ years that is significant either statistically, or in comparison to values associated with global warming. Unfortunately, the large interdecadal fluctuations of sealevel severely affect

Decelerating late Holocene sealevelrise over the south Florida platform has been accompanied by changes in sediment composition which reflect a transition from physically emplaced (allochthonous) sediment to biologically emplaced (autochthonous) sediment. This interpretation is based on a south Florida submergence curve which suggests that the rate of sealevelrise has decreased from 26 cm/100 years, prior to 3200 y.B.P., to 3.5 cm/100 years thereafter. These compositional changes are recognizable within both mixed siliciclastic/carbonate and pure carbonate depositional systems. For example, mangrove islands located in the Ten Thousand Islands area of southwest Florida are overlain by a Holocene sediment sequence which consists of (in ascending order) (1) thin basal mangrove peat, (2) thin oyster zone, (3) shelly quartz packstone, (4) oyster or vermetid packstone to boundstone, and (5) mangrove peat. The lower sequence (units 1 through 3) reflects an early deepening phase which accompanied a rapid rise in sealevel. Biological sediment production was not rapid enough to keep up with risingsealevel and, as such, the mangrove-fringed shoreline was overstepped. The overlying subtidal shelly quartz packstones reflect local reworking of Pleistocene quartz sands and, later, the introduction of quartz sand by suspension from offshore. As sealevelrise slowed, biological sediment production and accumulation began to exceed rates of sealevelrise and subsequently deposits built up to and kept pace with risingsealevel (units 4 and 5). Carbon-14 dates confirm this interpretation as the thin basal peats date at 4000 y.B.P. (rapid rise) and oysters at the base of unit 4 date at 1000 y.B.P. (slow rise).

Large parts of the Antarctic ice sheet lying on bedrock below sealevel may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-levelrise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

The Mississippi Delta (MD) and the adjacent US Gulf Coast host a significant population,extensive economic activity, and critical ecosystem goods and services. The characteristic rate of 20th century relative sealevelrise in the MD is ~10 mm/yr [e.g., Penland and Ramsey, 1990], which is about five times the global mean value. This regional amplification, thought to be dominated by land subsidence, makes this part of the Gulf Coast particularly vulnerable to catastrophic events (e.g., storm surges associated with tropical cyclones) as well as more chronic environmental degradation such as wetland loss from a range of largely human influences [Day et al., 2007]. This paper focuses on improving our understanding of land subsidence in this region via a modelling analysis that considers the influence of sediment loading as well as glacial isostatic adjustment (ice and ocean loading). A number of studies have suggested that sediment isostatic adjustment (SIA) and/or active tectonics are primary contributors to the present-day subsidence of this region [e.g. Dokka et al., 2006; Ivins et al., 2007] and thus contribute several mm/yr of regional basement subsidence. Our model sensitivity analysis considers key components of the regional sediment loading history as well as a range of plausible Earth model parameters. Results indicate that rates due to SIA are likely less that 0.5 mm/yr and those due to GIA can be up to ~2 mm/yr and so the latter plays a more important role. Model output was found to be compatible with both paleo (e.g. relative sealevel) and geodetic (Global Positioning System) observations. We therefore conclude that processes other than SIA and GIA, such as sediment compaction in the Holocene sediments, most likely dominate the high rates of sealevel change (~10 mm/yr) measured along this part of the Gulf Coast.

Studies on sealevelrise (SLR) in the context of climate change are gaining importance in the recent past. Whereas there is some clear evidence of SLR at global scale, its trend varies significantly from location to location. The role of different meteorological variables on sealevel change (SLC) is explored. We hypothesise that the role of such variables varies from location to location and modelling of local SLC requires a proper identification of specific role of individual factors. After identifying a group of various local meteorological variables, Supervised Principal Component Analysis (SPCA) is used to develop a location specific Combined Index (CI). The SPCA ensures that the developed CI possesses highest possible association with the historical SLC at that location. Further, using the developed CI, an attempt is made to model the local sealevel (LSL) variation in synchronous with the changing climate. The developed approach, termed as hydroclimatic semi-empirical approach, is found to be potential for local SLC at different coastal locations. The validated hydroclimatic approach is used for future projection of SLC at those coastal locations till 2100 for different climate change scenarios, i.e. different Representative Concentration Pathways (RCPs). Future hydrometeorological variables are obtained from Global Climate Models (GCMs) for different such scenarios, i.e. RCP2.6, RCP4.5 and RCP8.5. Effect of glacial isostatic readjustment (GIA) is not included in this study. However, if the reliable information on GIA is available for a location, the same can be arithmetically added to the final outcome of the proposed hydrometeorological approach.

During the last deglaciation (21,000 to 7,000years ago) global sealevelrise was punctuated by several abrupt meltwater spikes triggered by the retreat of ice sheets and glaciers world-wide. However, the debate regarding the relative timing, geographical source and the physical mechanisms driving these rapid increases in sealevel has catalyzed debate critical to predicting future sealevelrise and climate. Here we present a unique record of West Antarctic Ice Sheet elevation change derived from the Patriot Hills blue ice area, located close to the modern day grounding line of the Institute Ice Stream in the Weddell Sea Embayment. Combined isotopic signatures and gas volume analysis from the ice allows us to develop a record of local ice sheet palaeo-altitude that is assessed against independent regional high-resolution ice sheet modeling studies, allowing us to demonstrate that past ice sheet elevations across this sector of the WSE were considerably higher than those suggested by current terrestrial reconstructions. We argue that ice in the WSE had a significant influence on both pre and post LGM sealevelrise including MWP-1A (~14.6 ka) and during MWP-1B (11.7-11.6 ka), reconciling past sealevelrise and demonstrating for the first time that this sector of the WAIS made a significant and direct contribution to post LGM sealevelrise.

Global warming, or the increasing of earth's temperatures, leads to risingsealevel as polar ice caps and mountain glaciers melt and ocean water undergoes thermal expansion. Tidal records collected by the U.S. Army Corps of Engineers (COE), Mobile District, at Gulfport, Biloxi, and Pascagoula, Mississippi, and at Mobile, Alabama, indicate trends of water-surface elevations increasing with time (relative sea-levelrise). The trends indicated by the COE data were compared to relative sea-level trends indicated by the National Ocean Survey gages in the Gulf of Mexico. The average global rate of sealevelrise has been suggested to approach about 2 mm/yr (0.007 ft/yr). Some leading scientists have suggested rates of sealevelrise that are greater than 2 mm/yr, when accounting for effects of greenhouse gas emissions. As the sealevelrises and inundates the coastal plain, structures along the existing coast and structures located in the back bays of estuaries will be even more adversely affected by future flooding. Also, if the land surface adjacent to the water also sinks due to soil compaction and other geologic processes (collectively call subsidence), additional land will be inundated. Copyright ASCE 2004.

A variable-density groundwater flow and dispersive solute transport model was developed for the shallow coastal aquifer system near a municipal supply well field in southeastern Florida. The model was calibrated for a 105-year period (1900 to 2005). An analysis with the model suggests that well-field withdrawals were the dominant cause of salt water intrusion near the well field, and that historical sea-levelrise, which is similar to lower-bound projections of future sea-levelrise, exacerbated the extent of salt water intrusion. Average 2005 hydrologic conditions were used for 100-year sensitivity simulations aimed at quantifying the effect of projected rises in sealevel on fresh coastal groundwater resources near the well field. Use of average 2005 hydrologic conditions and a constant sealevel result in total dissolved solids (TDS) concentration of the well field exceeding drinking water standards after 70 years. When sea-levelrise is included in the simulations, drinking water standards are exceeded 10 to 21 years earlier, depending on the specified rate of sea-levelrise.

The effects of risingsealevel on the hydraulic balance between aquifers and the ocean threaten freshwater resources and aquatic ecosystems along many world coastlines. Understanding both the vulnerability of groundwater systems to these changes and the primary factors that determine the magnitude of system response is critical to developing effective management plans in coastal zones. The rate and magnitude of salinization of fresh groundwater due to lateral seawater intrusion and changes in groundwater flow to the sea were assessed over a range of hydrogeologic settings. A primary factor affecting vulnerability is whether the system is recharge-limited or topography-limited. Results of two-dimensional variable-density groundwater-flow and salt-transport simulations indicate that the response of recharge-limited systems is largely minimal, whereas topography-limited systems are vulnerable for various combinations of permeability, vertical anisotropy in permeability, and recharge. World coastlines were classified according to system type as a vulnerability indicator. Results indicate that more than 50 percent of world coastlines are topography-limited over the range of cases tested. Central coastal Bangladesh is an example of a primarily topography-limited system that is highly vulnerable to impacts of sea-levelrise as a result of its low elevation, dense population, and extensive groundwater use. Complexities of geologic heterogeneity and salinization processes, including storm-surge overtopping and accelerated salinization rates due to pumping, were considered. Results indicate that geologic heterogeneity has a strong control on the current and evolving pattern of salinity. The process of lateral intrusion can be slow, such that the current salinity distribution may still be changing in response to past sea-levelrise. Vertical intrusion from above, where it occurs, is faster, and pumping can accelerate both mechanisms. Bangladesh vulnerability analyses are

Risingsealevel represents a significant threat to coastal communities and ecosystems through land loss, altered habitats, and increased vulnerability to coastal storms and inundation. This threat is exemplified in the northern Gulf of Mexico where low topography, expansive marshes, and a prevalence of tropical storms have already resulted in extensive coastal impacts. The development of robust predictive capabilities that incorporate complex biological processes with physical dynamics are critical for informed planning and restoration efforts for coastal ecosystems. Looking to build upon existing predictive modeling capabilities and allow for use of multiple model (i.e., ensemble) approaches, NOAA initiated the Ecological Effects of SeaLevelRise program in 2010 to advance physical/biological integrative modeling capabilities in the region with a goal to provide user friendly predictive tools for coastal ecosystem management. Focused on the northern Gulf of Mexico, this multi-disciplinary project led by the University of Central Florida will use in situ field studies to parameterize physical and biological models. These field studies will also result in a predictive capability for overland sediment delivery and transport that will further enhance marsh, oyster, and submerged aquatic vegetation models. Results from this integrated modeling effort are envisioned to inform management strategies for reducing risk, restoration and breakwater guidelines, and resource sustainability for project planning, among other uses. In addition to the science components, this project incorporates significant engagement of the management community through a management applications principle investigator and an advisory management committee. Routine engagement between the science team and the management committee, including annual workshops, are focused on ensuring the development of applicable, relevant, and useable products and tools at the conclusion of this project. Particular

Freshwater peatlands can be dense carbon stores and are ecologically diverse with many specialised organisms. Climate-related threats to carbon storage include increases in rates of oxidation and methanogenesis, increases in drainage and dissolved organic carbon export from run off. Due to their lowland locations, coastal freshwater peatlands are at increasing risk from sealevelrise and is expected to result in ecosystem shifts with impacts on carbon stores and species diversity. Fed by a network of rivers and lakes in close proximity to the coast, the Broads, UK, is a series of freshwater peatlands at risk of increased incursion of saline water coupled with increased frequency and intensity of flooding events due to an anticipated sealevelrise of 3-5 cm decade-1 compounded by a predicted isotactic sinking of 0.055 cm yr-1. This study attempts to unravel the risks posed by sealevelrise to carbon stored in coastal freshwater peatlands. Near surface cores (~50 cm long) collected from three sites were analysed for bulk density and carbon content, and dated radiometrically (lead-210, cesium-137) to ascertain carbon accumulation. To understand loss by leaching and microbial decomposition, mass loss from litterbags was measured over one year. Results indicated that recent carbon accumulation rate (since 1964) was significantly higher (p < 0.001) at the site inundated for the longest period throughout the year (94 ± 0.17 g C m-2 yr-1) and lowest at the least inundated site (79 ± 0.17 g C m-2 yr-1). Accretion rates over the last two years were highest in the site with the most fluctuating water table (0.55 ± 0.13 cm yr-1) and lowest at the driest site (0.25 ± 0.04 cm yr-1). Proportion of mass loss was significantly different between sites for both leaves (p < 0.001) and stems (p < 0.001). Overall, this research has shown that extent of inundation can influence recent accumulation rate and proportion of mass loss.

Shoreline response to sealevelrise has been extensively studied, but relatively little work has examined potential changes to tidal inlet systems, of which there are more than 70 on the U. S. Atlantic coast. Sealevelrise can influence the hydrodynamics of an inlet system by flooding adjacent low-lying regions and changing distribution of wetland vegetation in the back barrier basin. If sealevelrise causes wetland vegetation loss, a basin's tidal prism can increase by: (1) conversion of previously vegetated marsh land to open water, and/or (2) tidal wave attenuation reduction in the basin, which increases efficiency of tidal exchange. In this study, we used a simple conceptual model paired with empirical relationships to investigate how two Florida inlets, Saint Augustine Inlet and Ponce de Leon Inlet, with contrasting wetland configurations, are expected to respond to wetland loss. While both inlets have similar areas of vegetated wetland, the distributions of vegetation throughout the basins differ. For both inlets, the model indicates that a loss in wetland area leads to an increase in tidal prism, cross-sectional area, and ebb shoal volume. At the Saint Augustine Inlet basin, the wetland vegetation is mostly fringing, creating a main basin channel with little tidal wave attenuation. The Ponce de Leon Inlet site has a more complex tidal channel network in the back basin, which is caused the presence of numerous marsh islands. The tortuous path that flood tidal water must travel during a tidal exchange causes higher spatial rates of tidal wave attenuation. Wetland loss at the Ponce de Leon Inlet site should increase the tidal prism of the system through both aforementioned mechanisms, whereas wetland loss at the Saint Augustine Inlet site should change the tidal prism only by increasing basin area. We conclude that tidal inlets with greater initial tidal wave attenuation have the potential to experience greater increases in tidal prism due to wetland loss

Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-levelrise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr(-1) carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km(2) (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sealevel, which are potentially vulnerable to inundation.

A rapidly melting ice sheet produces a distinctive geometry, or fingerprint, of sealevel (SL) change. Thus, a network of SL observations may, in principle, be used to infer sources of meltwater flux. We outline a formalism, based on a modified Kalman smoother, for using tide gauge observations to estimate the individual sources of global SL change. We also report on a series of detection experiments based on synthetic SL data that explore the feasibility of extracting source information from SL records. The Kalman smoother technique iteratively calculates the maximum-likelihood estimate of Greenland ice sheet (GIS) and West Antarctic ice sheet (WAIS) melt at each time step, and it accommodates data gaps while also permitting the estimation of nonlinear trends. Our synthetic tests indicate that when all tide gauge records are used in the analysis, it should be possible to estimate GIS and WAIS melt rates greater than ∼0.3 and ∼0.4 mm of equivalent eustatic sealevelrise per year, respectively. We have also implemented a multimodel Kalman filter that allows us to account rigorously for additional contributions to SL changes and their associated uncertainty. The multimodel filter uses 72 glacial isostatic adjustment models and 3 ocean dynamic models to estimate the most likely models for these processes given the synthetic observations. We conclude that our modified Kalman smoother procedure provides a powerful method for inferring melt rates in a warming world.

Laguna Madre, Texas, is 3-7 km wide and more than 190 km long, making it one of the longest lagoons in the world. The lagoon encompasses diverse geologic and climatic regions and it is an efficient sediment trap that accumulates clastic sediments from upland, interior, and oceanic sources. The semi-arid climate and frequent tropical cyclones historically have been responsible for the greatest volume of sediment influx. On an average annual basis, eolian transport, tidal exchange, storm washover, mainland runoff, interior shore erosion, and authigenic mineral production introduce approximately one million m3 of sediments into the lagoon. Analyses of these sediment transport mechanisms and associated line sources and point sources of sediment provide a basis for: (1) estimating the long-term average annual sediment supply to a large lagoon; (2) calculating the average net sedimentation rate; (3) comparing introduced sediment volumes and associated aggradation rates with observed relative sea-level change; and (4) predicting future conditions of the lagoon. This comparison indicates that the historical average annual accumulation rate in Laguna Madre (<1 mm/yr) is substantially less than the historical rate of relative sea-levelrise (~4 mm/yr). Lagoon submergence coupled with erosion of the western shore indicates that Laguna Madre is being submerged slowly and migrating westward rather than filling, as some have suggested.

A rapidly melting ice sheet produces a distinctive geometry, or fingerprint, of sealevel (SL) change. Thus, a network of SL observations may, in principle, be used to infer sources of meltwater flux. We outline a formalism, based on a modified Kalman smoother, for using tide gauge observations to estimate the individual sources of global SL change. We also report on a series of detection experiments based on synthetic SL data that explore the feasibility of extracting source information from SL records. The Kalman smoother technique iteratively calculates the maximum-likelihood estimate of Greenland ice sheet (GIS) and West Antarctic ice sheet (WAIS) melt at each time step, and it accommodates data gaps while also permitting the estimation of nonlinear trends. Our synthetic tests indicate that when all tide gauge records are used in the analysis, it should be possible to estimate GIS and WAIS melt rates greater than ∼0.3 and ∼0.4 mm of equivalent eustatic sealevelrise per year, respectively. We have also implemented a multimodel Kalman filter that allows us to account rigorously for additional contributions to SL changes and their associated uncertainty. The multimodel filter uses 72 glacial isostatic adjustment models and 3 ocean dynamic models to estimate the most likely models for these processes given the synthetic observations. We conclude that our modified Kalman smoother procedure provides a powerful method for inferring melt rates in a warming world.

Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-levelrise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr‑1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sealevel, which are potentially vulnerable to inundation.

Sealevelrise (SLR) may degrade habitat for coastal vertebrates in the Southeastern United States, but it is unclear which groups or species will be most exposed to habitat changes. We assessed 28 coastal Georgia vertebrate species for their exposure to potential habitat changes due to SLR using output from the SeaLevel Affecting Marshes Model and information on the species' fundamental niches. We assessed forecasted habitat change up to the year 2100 using three structural habitat metrics: total area, patch size, and habitat permanence. Almost all of the species ( n = 24) experienced negative habitat changes due to SLR as measured by at least one of the metrics. Salt marsh and ocean beach habitats experienced the most change (out of 16 categorical land cover types) across the three metrics and species that used salt marsh extensively (rails and marsh sparrows) were ranked highest for exposure to habitat changes. Species that nested on ocean beaches (Diamondback Terrapins, shorebirds, and terns) were also ranked highly, but their use of other foraging habitats reduced their overall exposure. Future studies on potential effects of SLR on vertebrates in southeastern coastal ecosystems should focus on the relative importance of different habitat types to these species' foraging and nesting requirements. Our straightforward prioritization approach is applicable to other coastal systems and can provide insight to managers on which species to focus resources, what components of their habitats need to be protected, and which locations in the study area will provide habitat refuges in the face of SLR.

Abstract Erosion caused in the coastal area of Togo especially in the cell to the east of the harbor of Lomé some reorganization of space and a reallocation of tasks functions of the importance of existing issues. This reorganization is an important race against time between the various stakeholders which paradoxically make this area a very dynamic environment. In spite of the disaster situation in the area, it is changing. This mutation has been observed for a decade in many ways. Fishing is a traditional activity disappears causing the emergence of new activities such as the extraction of gravel, the gardening, the informal trade of any kind, installing hotels, etc.. At the socio-economic transformation is associated with a beach in state of deficit causing the decline of the coastline that reaches approximately 500 m over a few kilometers according to the old marks missing. The decline of the coastline is by undermining the beach by the waves at high tide. These issues are reshaping the land use map that passes a distribution of fishing villages on the coast in 1980 to a suburban area exposed to sealevelrise corollary to anticipated climate change. Keywords: Space, Reorganization, Vulnerability, Stakeholders, SeaLevel, Fishing

Sealevelrise (SLR) may degrade habitat for coastal vertebrates in the Southeastern United States, but it is unclear which groups or species will be most exposed to habitat changes. We assessed 28 coastal Georgia vertebrate species for their exposure to potential habitat changes due to SLR using output from the SeaLevel Affecting Marshes Model and information on the species' fundamental niches. We assessed forecasted habitat change up to the year 2100 using three structural habitat metrics: total area, patch size, and habitat permanence. Almost all of the species (n = 24) experienced negative habitat changes due to SLR as measured by at least one of the metrics. Salt marsh and ocean beach habitats experienced the most change (out of 16 categorical land cover types) across the three metrics and species that used salt marsh extensively (rails and marsh sparrows) were ranked highest for exposure to habitat changes. Species that nested on ocean beaches (Diamondback Terrapins, shorebirds, and terns) were also ranked highly, but their use of other foraging habitats reduced their overall exposure. Future studies on potential effects of SLR on vertebrates in southeastern coastal ecosystems should focus on the relative importance of different habitat types to these species' foraging and nesting requirements. Our straightforward prioritization approach is applicable to other coastal systems and can provide insight to managers on which species to focus resources, what components of their habitats need to be protected, and which locations in the study area will provide habitat refuges in the face of SLR.

Sealevelrise (SLR) may degrade habitat for coastal vertebrates in the Southeastern United States, but it is unclear which groups or species will be most exposed to habitat changes. We assessed 28 coastal Georgia vertebrate species for their exposure to potential habitat changes due to SLR using output from the SeaLevel Affecting Marshes Model and information on the species’ fundamental niches. We assessed forecasted habitat change up to the year 2100 using three structural habitat metrics: total area, patch size, and habitat permanence. Almost all of the species (n = 24) experienced negative habitat changes due to SLR as measured by at least one of the metrics. Salt marsh and ocean beach habitats experienced the most change (out of 16 categorical land cover types) across the three metrics and species that used salt marsh extensively (rails and marsh sparrows) were ranked highest for exposure to habitat changes. Species that nested on ocean beaches (Diamondback Terrapins, shorebirds, and terns) were also ranked highly, but their use of other foraging habitats reduced their overall exposure. Future studies on potential effects of SLR on vertebrates in southeastern coastal ecosystems should focus on the relative importance of different habitat types to these species’ foraging and nesting requirements. Our straightforward prioritization approach is applicable to other coastal systems and can provide insight to managers on which species to focus resources, what components of their habitats need to be protected, and which locations in the study area will provide habitat refuges in the face of SLR.

The response of tidally driven processes on the Patagonian Shelf to sea-levelrise (SLR) is revisited using large but realistic levels of change in a numerical tidal model. The results relate to previous studies through significant differences in the impact, depending on how SLR is implemented. This is true for how the boundary at the coastline is treated, i.e., if we allow for inundation of land or assume flood defences along the coast, but also for how the sea-level change itself is implemented. Simulations with uniform SLR provide a different, and slightly larger, response than do runs where SLR is based on observed trends. In all cases, the effect on the tidal amplitudes is patchy, with alternating increases and decreases in amplitude along the shelf. Furthermore, simulations with a realistic future change in vertical stratification, thus affecting tidal conversion rates, imply that there may be a small but significant decrease in the amplitudes along the coast. Associated processes, e.g., the location of mixing fronts and potential impacts on biogeochemical cycles on the shelf are also discussed.

Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-levelrise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr−1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sealevel, which are potentially vulnerable to inundation. PMID:27354088

The vast majority of our lifetime is spent learning outside the classroom, yet the major emphasis in developing climate change instructional materials has been the traditional K16 school environment. The Polar Learning and Responding (PoLAR) project of the National Science Foundation supported Climate Change Education Partnership (CCEP) program chose to move beyond the classroom to focus on lifelong learners, in order to engage the adult population in building public understanding about climate change. Yet reaching individuals who make their own decisions about what and how they choose to learn requires a very different approach to developing educational materials. With an adult audience how we deliver content can be as critical as what we deliver. Using materials and platforms that are readily available and familiar to the user is important. With a significant segment of our time spent connected to smart phones and tablets, employing these platforms to deliver content makes sense. Whether at work, home or in transit, portable devices are critical companions and trusted tools in providing information on everything from the latest news to the daily weather. The world of Apps is equally as familiar to the adult user, so developing an engaging climate App for a portable device offers a successful strategy. The 'Polar Explorer - SeaLevelRise (SLR) App', is one of the new interactive products developed as part of the PoLAR project. Modeled after Columbia's Earth Observer App, a data exploration and data visualization tool, the Polar Explorer SLR App includes a wide range of real Earth data from ocean and atmospheric temperatures to depth of ice layers, underlying topography and human impacts. The Polar Explorer SLR App is grounded in the concept that scientists gain insights into climate change and climate processes through directly examining data. With some scaffolding, the public can gain similar insights using the same data. Structured to be 'question driven' the

Global sealevels have been rising through the past century and are projected to rise at an accelerated rate throughout the 21st century. This has motivated a number of authors to search for already existing accelerations in observations, which would be, if present, vital for coastal protection planning purposes. No scientific consensus has been reached yet as to how a possible acceleration could be separated from intrinsic climate variability in sealevel records. This has led to an intensive debate on its existence and, if absent, also on the general validity of current future projections. Here we shed light on the controversial discussion from a methodological point of view. To do so, we provide a comprehensive review of trend methods used in the community so far. This resulted in an overview of 30 methods, each having its individual mathematical formulation, flexibilities, and characteristics. We illustrate that varying trend approaches may lead to contradictory acceleration-deceleration inferences. As for statistics-oriented trend methods, we argue that checks on model assumptions and model selection techniques yield a way out. However, since these selection methods all have implicit assumptions, we show that good modeling practices are of importance too. We conclude at this point that (i) several differently characterized methods should be applied and discussed simultaneously, (ii) uncertainties should be taken into account to prevent biased or wrong conclusions, and (iii) removing internally generated climate variability by incorporating atmospheric or oceanographic information helps to uncover externally forced climate change signals.

Erosion of the estuarine shoreline along barrier islands (the back-barrier shoreline) is a prevalent but often overlooked mechanism of island narrowing. In response to sea-levelrise and storms, back-barrier shorelines of all barrier types erode, and without wash-over to replenish losses the island will narrow. Typically, the most seaward dune ridge on a progradational barrier is at the highest elevation, which may prevent overwash for millennia, contributing to high rates of erosion along the back-barrier. Upon continued narrowing, regressive barriers may reach a critical width when wash-over occurs, causing the island to become transgressive. This conceptual model suggests that the transition of a barrier from regressive to transgressive may have a threshold response to forcing mechanisms, namely sediment supply, climate variation, underlying geologic framework, rate of sea-levelrise and anthropogenic influence. The study area is Bogue Banks, North Carolina, because this barrier has two wide regressive segments separated by a narrow center segment that we show was regressive in the past. Boomer seismic data collected offshore reveal the presence of multiple paleochannels that spatially correlate to the regressive portions of the island. Vibracore transects taken from the center portion of the back-barrier exhibit shoreface sand overlain by lagoonal muddy sand. These two units are separated by a bay-ravinement surface. Long Island, located in the lagoon along the central segment of the island is interpreted as a remnant beach ridge. Samples for optically stimulated luminescence dating and radiocarbon dating were taken to identify the age of barrier development and subsequent erosion of the central segment, respectively. Regression started along Bogue Banks ~3000 cal yr. BP, as the rate of relative sea-levelrise slowed to ~0.8 mm/ yr. Reworked fluvial sediment from offshore paleochannels was an important sediment source. Regression continued to ~1100 cal yr. BP

The problem of forecasting the future behaviour of the Antarctic ice sheet is considered. We describe a method for optimizing this forecast by combining a model of ice sheet flow with observations. Under certain assumptions, a linearized model of glacial flow can be combined with observations of the thickness change, snow accumulation, and ice-flow, to forecast the Antarctic contribution to sea-levelrise. Numerical simulations show that this approach can potentially be used to test whether changes observed in Antarctica are consistent with the natural forcing of a stable ice sheet by snowfall fluctuations. To make predictions under less restrictive assumptions, improvements in models of ice flow are needed. Some of the challenges that this prediction problem poses are highlighted, and potentially useful approaches drawn from numerical weather prediction are discussed.

The Adriatic/Dinaric carbonate platform of Yugoslavia was influenced by rapid sealevelrise and an oceanic anoxic event during the Cenomanian-Turonian. Open-marine biota such as planktonic foraminifera, radiolarians, and locally even ammonites, associated with and bracketed by successions of typical shallow-water carbonates, indicate partial drowning of substantial areas of the platform during this time, suggestive furthermore that the rate of increase of water depth was locally great enough to outpace carbonate production. The presence of carbon-rich and fish-bearing platy limestones, commonly cherty, as an associated coeval facies indicates the development of anoxic or euxinic environments, and the stromatolitic laminations in such rocks are attributed to the action of bacterial mats. It is suggested that an extensive column of deoxygenated water developed in the neighboring Marche-Umbrian-Adriatic deep-water basin and was carried on to the carbonate platform during the Cenomanian-Turonian transgression.

Risingsealevel along the relatively flat southeastern US coastal plain significantly changes both vegetation composition and salinity of coastal wetlands, eventually modifying ecosystem functions and biogeochemical processes of these wetlands. We conducted a two-year study to evaluate the dynamics and relationships among aboveground productivity, greenhouse and halocarbon gas emissions, nutrients, and dissolved organic matter of a freshwater forested wetland, a salt-impacted and degraded forested wetland, and a salt marsh in Winyah Bay, South Carolina, representing the salinity gradient and the transition from freshwater forested wetland to salt marsh due to sealevelrise. The degraded forested wetland had significantly lower above-ground productivity with annual stem growth of 102 g/m^2/yr and litterfall of 392 g/m^2/yr compared to the freshwater forested wetland (230 and 612 g/m^2/yr, respectively). High methane emission [> 50 mmol/m2/day, n = 4] was only observed in the freshwater-forested wetland but there was a strong smell of sulfide noticed in the salt marsh, suggesting that different redox processes control the decomposition of natural organic matter along the salinity gradient. In addition, the largest CHCl3 [209 × 183 nmol/m2/day, n = 4] emission was observed in the degraded forested wetland, but net CH3Cl [257 × 190 nmol/m2/day, n = 4] and CH3Br [28 × 20 nmol/m2/day, n = 4] emissions were only observed in the salt marsh, suggesting different mechanisms in response to salt intrusion at that sites. The highest DOC concentration (28 - 42 mg/L) in monthly water samples was found in degraded forest wetland, followed by the freshwater forested wetland (19 - 38 mg/L) and salt marsh (9 - 18 mg/L). Results demonstrate that the salt-impacted degraded wetland has unique biogeochemical cycles that differ from unaltered freshwater forested wetland and salt marsh.

The Gio Linh district in the Quang Tri province, Central Vietnam has, like many other coastal areas in the world, to deal with negative impacts of Global Climate Change (GCC) and sealevelrise (SLR). This research aims at investigating the impact of GCC/SLR and designing an adaptive water use plan till the year 2030 for the local residents of the Gio Linh district. This coastal plain covers an area of about 450 km2 and is situated between the rivers Ben Hai in the North and Thach Han in the South. The elevation varies from 0.5 m at the seaside in the East to 19.5 m further inland. During the rainy season from August to April the precipitation is on average 2000 to 2700 mm. GCC/SLR scenarios are built and assessed for estimating the changes in hydrometeorological conditions of the study area. Depending on the level of gas emission the sealevel is expected to rise 7-9 cm by 2020 and around 11-14 cm by 2030 for low to high gas emission respectively. The salt-freshwater interface is expected to experience an inland shift due to SLR, affecting the amount of exploitable groundwater for drinking and irrigation water production. Drinking water production mainly comes from shallow aquifers in unconsolidated Quarternary coastal formations. A SEAWAT groundwater model will be built to study the effects on the groundwater system. Data from meteorological stations over a period of about 30 years and data from 63 boreholes in and around the Gio Linh district are available. Historical production records of an operational groundwater production well-field are available to be used for validation of the model. Finally, to achieve a sustainable integrated water resources management in the Gio Linh district different adaptive scenarios will be developed.

There is increasing awareness of the need for transdisciplinary science to address complex climate change issues, yet practical guidance is lacking. This presentation describes the iterative planning, implementation, and evaluation process of an ongoing transdisciplinary sealevelrise (SLR) research project. Observations, reflections, and recommendations from firsthand experience are shared, illustrated with examples, and placed within a transdisciplinary research framework. The NOAA-sponsored project, Ecological Effects of SeaLevelRise in the Northern Gulf of Mexico (EESLR-NGOM) is a six-year regional study involving a team of biology, ecology, civil/coastal engineering, and communication scholars working with government agency personnel and industry professionals; supervising students and post-doctoral researchers; and engaging a group of non-academic stakeholders (i.e., coastal resource managers). EESLR-NGOM's focus is on detailed assessment and process-based modeling to project SLR impacts on northern Gulf of Mexico coastal wetland habitats and flood plains. This presentation highlights collaboration, communication, and project management considerations, and explains knowledge co-production from a dynamic combination of natural and social scientific methods (secondary data analysis, computer modeling, field observations, field and laboratory experiments, focus group interviews, surveys) and interrelated stakeholder engagement mechanisms (advisory committee, project flow chart, workshops, focus groups, webinars) infused throughout the EESLR-NGOM project to improve accessibility and utility of the scientific results and products. Attention is also given to project evaluation including monitoring, multiple quantitative and qualitative measures, and recognition of challenges and limitations. This presentation should generate productive dialogue and direction for similar endeavors to find transformative solutions to pressing problems of climate change.

Northwest Alaska is experiencing significant climate change and human impacts. The study area includes the coastal zone of Kotzebue Sound and the Chukchi Sea and provides the local population (predominantly Inupiaq Eskimo) with critical subsistence resources of meat, fish, berries, herbs, and wood. The geomorphology of the coast includes barrier islands, inlets, estuaries, deltas, cliffs, bluffs, and beaches that host modern settlements and infrastructure. Coastal dynamics and sea-levelrise are contributing to erosion, intermittent erosion/accretion patterns, landslides, slumps and coastal retreat. These factors are causing the sedimentation of deltas and lagoons, and changing local bathymetry, morphological parameters of beaches and underwater slopes, rates of coastal dynamics, and turbidity and nutrient cycling in coastal waters. This study is constructing vulnerability maps to help local people and federal officials understand the potential consequences of sea-levelrise and coastal erosion on local infrastructure, subsistence resources, and culturally important sites. A lack of complete and uniform data (in terms of methods of collection, geographic scale and spatial resolution) creates an additional level of uncertainty that complicates geographic analysis. These difficulties were overcome by spatial modeling with selected spatial resolution using extrapolation methods. Data include subsistence resource maps obtained using Participatory GIS with local hunters and elders, geological and geographic data on coastal dynamics from satellite imagery, aerial photos, bathymetry and topographic maps, and digital elevation models. These data were classified and ranked according to the level of coastal vulnerability (Figure 1). The resulting qualitative multicriteria model helps to identify the coastal areas with the greatest vulnerability to coastal erosion and of the potential loss of subsistence resources. Acknowldgements: Dr. Ron Abileah (private consultant, j

Future climate simulations based on the Intergovernmental Panel on Climate Change emissions scenario (A1B) have shown that the Skagit River flow will be affected, which may lead to modification of the estuarine hydrodynamics. There is considerable uncertainty, however, about the extent and magnitude of resulting change, given accompanying sealevelrise and site-specific complexities with multiple interconnected basins. To help quantify the future hydrodynamic response, we developed a three dimensional model of the Skagit River estuary using the Finite Volume Coastal Ocean Model (FVCOM). The model was set up with localized high-resolution grids in Skagit and Padilla Bay sub-basins within the intermediate-scale FVCOM based model of the Salish Sea (greater Puget Sound and Georgia Basin). Future changes to salinity and annual transport through the basin were examined. The results confirmed the existence of a residual estuarine flow that enters Skagit Bay from Saratoga Passage to the south and exits through Deception Pass. Freshwater from the Skagit River is transported out in the surface layers primarily through Deception Pass and Saratoga Passage, and only a small fraction (≈4%) is transported to Padilla Bay. The moderate future perturbations of A1B emissions, corresponding river flow, and sealevelrise of 0.48 m examined here result only in small incremental changes to salinity structure and inter-basin freshwater distribution and transport. An increase in salinity of ~1 ppt in the near-shore environment and a salinity intrusion of approximately 3 km further upstream is predicted in Skagit River, well downstream of the drinking water intakes.

The accuracy with which coastal topography has been mapped directly affects the reliability and usefulness of elevationbased sea-levelrise vulnerability assessments. Recent research has shown that the qualities of the elevation data must be well understood to properly model potential impacts. The cumulative vertical uncertainty has contributions from elevation data error, water level data uncertainties, and vertical datum and transformation uncertainties. The concepts of minimum sealevel rise increment and minimum planning timeline, important parameters for an elevation-based sea-levelrise assessment, are used in recognition of the inherent vertical uncertainty of the underlying data. These concepts were applied to conduct a sea-levelrise vulnerability assessment of the Mobile Bay, Alabama, region based on high-quality lidar-derived elevation data. The results that detail the area and associated resources (land cover, population, and infrastructure) vulnerable to a 1.18-m sea-levelrise by the year 2100 are reported as a range of values (at the 95% confidence level) to account for the vertical uncertainty in the base data. Examination of the tabulated statistics about land cover, population, and infrastructure in the minimum and maximum vulnerable areas shows that these resources are not uniformly distributed throughout the overall vulnerable zone. The methods demonstrated in the Mobile Bay analysis provide an example of how to consider and properly account for vertical uncertainty in elevation-based sea-levelrise vulnerability assessments, and the advantages of doing so.

Sea-levelrise (SLR) can modify not only total water levels, but also tidal dynamics. Several studies have investigated the effects of SLR on the tides of the western European continental shelf (mainly the M2 component). We further investigate this issue using a modelling-based approach, considering uniform SLR scenarios from -0.25 m to +10 m above present-day sealevel. Assuming that coastal defenses are constructed along present-day shorelines, the patterns of change in high tide levels (annual maximum water level) are spatially similar, regardless of the magnitude of sea-levelrise (i.e., the sign of the change remains the same, regardless of the SLR scenario) over most of the area (70%). Notable increases in high tide levels occur especially in the northern Irish Sea, the southern part of the North Sea and the German Bight, and decreases occur mainly in the western English Channel. These changes are generally proportional to SLR, as long as SLR remains smaller than 2 m. Depending on the location, they can account for +/-15% of regional SLR. High tide levels and the M2 component exhibit slightly different patterns. Analysis of the 12 largest tidal components highlights the need to take into account at least the M2, S2, N2, M4, MS4 and MN4 components when investigating the effects of SLR on tides. Changes in high tide levels are much less proportional to SLR when flooding is allowed, in particular in the German Bight. However, some areas (e.g., the English Channel) are not very sensitive to this option, meaning that the effects of SLR would be predictable in these areas, even if future coastal defense strategies are ignored. Physically, SLR-induced tidal changes result from the competition between reductions in bed friction damping, changes in resonance properties and increased reflection at the coast, i.e., local and non-local processes. A preliminary estimate of tidal changes by 2100 under a plausible non-uniform SLR scenario (using the RCP4.5 scenario) is

The range of future climate-induced sea-levelrise remains highly uncertain with continued concern that large increases in the twenty-first century cannot be ruled out. The biggest source of uncertainty is the response of the large ice sheets of Greenland and west Antarctica. Based on our analysis, a pragmatic estimate of sea-levelrise by 2100, for a temperature rise of 4°C or more over the same time frame, is between 0.5 m and 2 m--the probability of rises at the high end is judged to be very low, but of unquantifiable probability. However, if realized, an indicative analysis shows that the impact potential is severe, with the real risk of the forced displacement of up to 187 million people over the century (up to 2.4% of global population). This is potentially avoidable by widespread upgrade of protection, albeit rather costly with up to 0.02 per cent of global domestic product needed, and much higher in certain nations. The likelihood of protection being successfully implemented varies between regions, and is lowest in small islands, Africa and parts of Asia, and hence these regions are the most likely to see coastal abandonment. To respond to these challenges, a multi-track approach is required, which would also be appropriate if a temperature rise of less than 4°C was expected. Firstly, we should monitor sealevel to detect any significant accelerations in the rate of rise in a timely manner. Secondly, we need to improve our understanding of the climate-induced processes that could contribute to rapid sea-levelrise, especially the role of the two major ice sheets, to produce better models that quantify the likely future rise more precisely. Finally, responses need to be carefully considered via a combination of climate mitigation to reduce the rise and adaptation for the residual rise in sealevel. In particular, long-term strategic adaptation plans for the full range of possible sea-levelrise (and other change) need to be widely developed.

Over the time scale of centuries gradual sealevelrise will carry significant impacts for all human infrastructures and natural ecosystems that lie close to mean sealevel at present. But for the next few decades another aspect of sealevelrise will likely pack the stronger punch. Even at present, episodic storm surges may create significant damage, and consideration of their return levels for long periods (50/100 years) have to be taken into account when planning structures or protecting pre-existing valuables, both within artificial and natural systems. When these same return levels are combined with the expected sealevelrise in the next few decades it is very likely that the risk assessment will have to change, since the return period of damaging events is going to be in all cases shortened, and in many cases substantially so. We present an analysis of mid-term projections of changes in return levels/return periods in storm surges for a network of gauges along the coasts of the US lower 48. Our study starts by assessing a measure of gauge-specific, i.e., local, sealevelrise, in light of which we propose to downscale future global sealevelrise projections at each location. We then detrend and subtract the tidal and seasonal cycle from each gauge record, and perform an analysis of the maximum seasonal values of the residuals, representing our best estimates of current storm surge statistics. After determining return levels for a number of representative periods we add in projections of sealevelrise. The latter we derive from a semi-empirical model recently proposed in the literature by Vermeer and Rahmstorf (2009). The analysis combines best estimates and ranges of uncertainty for each of the components into an overall assessment of the possible range of outcomes.

Albedo modification (AM) is sometimes characterized as a potential means of avoiding climate threshold responses, including large-scale ice sheet mass loss. Previous work has investigated the effects of AM on total sea-levelrise over the present century, as well as AM’s ability to reduce long-term (≫103 yr) contributions to sea-levelrise from the Greenland Ice Sheet (GIS). These studies have broken new ground, but neglect important feedbacks in the GIS system, or are silent on AM’s effectiveness over the short time scales that may be most relevant for decision-making (<103 yr). Here, we assess AM’s ability to reduce GIS sea-level contributions over decades to centuries, using a simplified ice sheet model. We drive this model using a business-as-usual base temperature forcing scenario, as well as scenarios that reflect AM-induced temperature stabilization or temperature drawdown. Our model results suggest that (i) AM produces substantial near-term reductions in the rate of GIS-driven sea-levelrise. However, (ii) sea-levelrise contributions from the GIS continue after AM begins. These continued sealevelrise contributions persist for decades to centuries after temperature stabilization and temperature drawdown begin, unless AM begins in the next few decades. Moreover, (iii) any regrowth of the GIS is delayed by decades or centuries after temperature drawdown begins, and is slow compared to pre-AM rates of mass loss. Combined with recent work that suggests AM would not prevent mass loss from the West Antarctic Ice Sheet, our results provide a nuanced picture of AM’s possible effects on future sea-levelrise.

Acceleratedsea-levelrise (SLR) is a major long term outcome of climate change leading to increased inundation of low-lying areas. Particularly, global cities that are located on or near the coasts are often situated in low lying areas and these locations put global cities at greater risk to SLR. Localized flooding will profoundly impact vulnerable communities located in high-risk urban areas. Building community resilience and adapting to SLR is increasingly a high priority for cities. On the other hand, Article 6 of the United Nations Framework Convention on Climate Change addresses the importance of climate change communication and engaging stakeholders in decision making process. Importantly, Community Based Adaptation (CBA) experiences emphasize that it is important to understand a community's unique perceptions of their adaptive capacities to identify useful solutions and that scientific and technical information on anticipated coastal climate impacts needs to be translated into a suitable language and format that allows people to be able to participate in adaptation planning. To address this challenge, this study has put forth three research questions from the lens of urban community engagement in SLR adaptation, (1) What, if any, community engagement in addressing SLR occurring in urban areas; (2) What information do communities need and how does it need to be communicated, in order to be better prepared and have a greater sense of agency? and (3) How can government agencies from city to federal levels facilitate community engagement and action?. To answer these questions this study has evolved a framework "COREDAR" (COmmunicating Risk of sealevelrise and Engaging stakeholDers in framing community based Adaptation StRategies) to communicate and transfer complex climate data and information such as projected SLR under different scenarios of IPCC AR5, predicted impact of SLR, prioritizing vulnerability, etc. to concerned stakeholders and local communities

The Dynamic Interactive Vulnerability Assessment Wetland Change Model (DIVA_WCM) comprises a dataset of contemporary global coastal wetland stocks (estimated at 756 × 103 km2 (in 2011)), mapped to a one-dimensional global database, and a model of the macro-scale controls on wetland response to sea-levelrise. Three key drivers of wetland response to sea-levelrise are considered: 1) rate of sea-levelrise relative to tidal range; 2) lateral accommodation space; and 3) sediment supply. The model is tuned by expert knowledge, parameterised with quantitative data where possible, and validated against mapping associated with two large-scale mangrove and saltmarsh vulnerability studies. It is applied across 12,148 coastal segments (mean length 85 km) to the year 2100. The model provides better-informed macro-scale projections of likely patterns of future coastal wetland losses across a range of sea-levelrise scenarios and varying assumptions about the construction of coastal dikes to prevent sea flooding (as dikes limit lateral accommodation space and cause coastal squeeze). With 50 cm of sea-levelrise by 2100, the model predicts a loss of 46-59% of global coastal wetland stocks. A global coastal wetland loss of 78% is estimated under high sea-levelrise (110 cm by 2100) accompanied by maximum dike construction. The primary driver for high vulnerability of coastal wetlands to sea-levelrise is coastal squeeze, a consequence of long-term coastal protection strategies. Under low sea-levelrise